Bump version to 0.0.81

This reverts commit 77e5564f4b.

Cargo.lock

@@ -64,6 +64,20 @@ dependencies = [
  "term",
 ]
 
+[[package]]
+name = "assert_cmd"
+version = "2.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93ae1ddd39efd67689deb1979d80bad3bf7f2b09c6e6117c8d1f2443b5e2f83e"
+dependencies = [
+ "bstr",
+ "doc-comment",
+ "predicates",
+ "predicates-core",
+ "predicates-tree",
+ "wait-timeout",
+]
+
 [[package]]
 name = "async-channel"
 version = "1.7.1"
@@ -404,9 +418,9 @@ checksum = "fff857943da45f546682664a79488be82e69e43c1a7a2307679ab9afb3a66d2e"
 
 [[package]]
 name = "clap"
-version = "4.0.9"
+version = "4.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "30607dd93c420c6f1f80b544be522a0238a7db35e6a12968d28910983fee0df0"
+checksum = "6bf8832993da70a4c6d13c581f4463c2bdda27b9bf1c5498dc4365543abe6d6f"
 dependencies = [
  "atty",
  "bitflags",
@@ -419,9 +433,9 @@ dependencies = [
 
 [[package]]
 name = "clap_derive"
-version = "4.0.9"
+version = "4.0.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a4a307492e1a34939f79d3b6b9650bd2b971513cd775436bf2b78defeb5af00b"
+checksum = "c42f169caba89a7d512b5418b09864543eeb4d497416c917d7137863bd2076ad"
 dependencies = [
  "heck",
  "proc-macro-error",
@@ -452,6 +466,16 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "codespan-reporting"
+version = "0.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3538270d33cc669650c4b093848450d380def10c331d38c768e34cac80576e6e"
+dependencies = [
+ "termcolor",
+ "unicode-width",
+]
+
 [[package]]
 name = "colored"
 version = "2.0.0"
@@ -574,12 +598,62 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "cxx"
+version = "1.0.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "19f39818dcfc97d45b03953c1292efc4e80954e1583c4aa770bac1383e2310a4"
+dependencies = [
+ "cc",
+ "cxxbridge-flags",
+ "cxxbridge-macro",
+ "link-cplusplus",
+]
+
+[[package]]
+name = "cxx-build"
+version = "1.0.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3e580d70777c116df50c390d1211993f62d40302881e54d4b79727acb83d0199"
+dependencies = [
+ "cc",
+ "codespan-reporting",
+ "once_cell",
+ "proc-macro2",
+ "quote",
+ "scratch",
+ "syn",
+]
+
+[[package]]
+name = "cxxbridge-flags"
+version = "1.0.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56a46460b88d1cec95112c8c363f0e2c39afdb237f60583b0b36343bf627ea9c"
+
+[[package]]
+name = "cxxbridge-macro"
+version = "1.0.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "747b608fecf06b0d72d440f27acc99288207324b793be2c17991839f3d4995ea"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "diff"
 version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "56254986775e3233ffa9c4d7d3faaf6d36a2c09d30b20687e9f88bc8bafc16c8"
 
+[[package]]
+name = "difflib"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6184e33543162437515c2e2b48714794e37845ec9851711914eec9d308f6ebe8"
+
 [[package]]
 name = "digest"
 version = "0.8.1"
@@ -658,6 +732,12 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "doc-comment"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
+
 [[package]]
 name = "either"
 version = "1.8.0"
@@ -928,8 +1008,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4eb1a864a501629691edf6c15a593b7a51eebaa1e8468e9ddc623de7c9b58ec6"
 dependencies = [
  "cfg-if 1.0.0",
+ "js-sys",
  "libc",
  "wasi 0.11.0+wasi-snapshot-preview1",
+ "wasm-bindgen",
 ]
 
 [[package]]
@@ -955,6 +1037,9 @@ name = "hashbrown"
 version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
+dependencies = [
+ "ahash",
+]
 
 [[package]]
 name = "heck"
@@ -991,17 +1076,28 @@ checksum = "dfa686283ad6dd069f105e5ab091b04c62850d3e4cf5d67debad1933f55023df"
 
 [[package]]
 name = "iana-time-zone"
-version = "0.1.50"
+version = "0.1.51"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fd911b35d940d2bd0bea0f9100068e5b97b51a1cbe13d13382f132e0365257a0"
+checksum = "f5a6ef98976b22b3b7f2f3a806f858cb862044cfa66805aa3ad84cb3d3b785ed"
 dependencies = [
  "android_system_properties",
  "core-foundation-sys",
+ "iana-time-zone-haiku",
  "js-sys",
  "wasm-bindgen",
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "iana-time-zone-haiku"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fde6edd6cef363e9359ed3c98ba64590ba9eecba2293eb5a723ab32aee8926aa"
+dependencies = [
+ "cxx",
+ "cxx-build",
+]
+
 [[package]]
 name = "idna"
 version = "0.3.0"
@@ -1085,9 +1181,15 @@ dependencies = [
 
 [[package]]
 name = "itoa"
-version = "1.0.3"
+version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6c8af84674fe1f223a982c933a0ee1086ac4d4052aa0fb8060c12c6ad838e754"
+checksum = "4217ad341ebadf8d8e724e264f13e593e0648f5b3e94b3896a5df283be015ecc"
+
+[[package]]
+name = "joinery"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72167d68f5fce3b8655487b8038691a3c9984ee769590f93f2a631f4ad64e4f5"
 
 [[package]]
 name = "js-sys"
@@ -1193,9 +1295,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.134"
+version = "0.2.135"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "329c933548736bc49fd575ee68c89e8be4d260064184389a5b77517cddd99ffb"
+checksum = "68783febc7782c6c5cb401fbda4de5a9898be1762314da0bb2c10ced61f18b0c"
 
 [[package]]
 name = "libcst"
@@ -1221,6 +1323,15 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "link-cplusplus"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9272ab7b96c9046fbc5bc56c06c117cb639fe2d509df0c421cad82d2915cf369"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "linked-hash-map"
 version = "0.5.6"
@@ -1506,18 +1617,18 @@ checksum = "b1de2e551fb905ac83f73f7aedf2f0cb4a0da7e35efa24a202a936269f1f18e1"
 
 [[package]]
 name = "path-absolutize"
-version = "3.0.13"
+version = "3.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d3de4b40bd9736640f14c438304c09538159802388febb02c8abaae0846c1f13"
+checksum = "0f1d4993b16f7325d90c18c3c6a3327db7808752db8d208cea0acee0abd52c52"
 dependencies = [
  "path-dedot",
 ]
 
 [[package]]
 name = "path-dedot"
-version = "3.0.17"
+version = "3.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d611d5291372b3738a34ebf0d1f849e58b1dcc1101032f76a346eaa1f8ddbb5b"
+checksum = "9a81540d94551664b72b72829b12bd167c73c9d25fbac0e04fafa8023f7e4901"
 dependencies = [
  "once_cell",
 ]
@@ -1685,6 +1796,33 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "925383efa346730478fb4838dbe9137d2a47675ad789c546d150a6e1dd4ab31c"
 
+[[package]]
+name = "predicates"
+version = "2.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a5aab5be6e4732b473071984b3164dbbfb7a3674d30ea5ff44410b6bcd960c3c"
+dependencies = [
+ "difflib",
+ "itertools",
+ "predicates-core",
+]
+
+[[package]]
+name = "predicates-core"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da1c2388b1513e1b605fcec39a95e0a9e8ef088f71443ef37099fa9ae6673fcb"
+
+[[package]]
+name = "predicates-tree"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4d86de6de25020a36c6d3643a86d9a6a9f552107c0559c60ea03551b5e16c032"
+dependencies = [
+ "predicates-core",
+ "termtree",
+]
+
 [[package]]
 name = "proc-macro-error"
 version = "1.0.4"
@@ -1907,9 +2045,10 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.60"
+version = "0.0.81"
 dependencies = [
  "anyhow",
+ "assert_cmd",
  "bincode",
  "cacache",
  "chrono",
@@ -1920,12 +2059,14 @@ dependencies = [
  "dirs 4.0.0",
  "fern",
  "filetime",
+ "getrandom 0.2.7",
  "glob",
  "insta",
  "itertools",
  "libcst",
  "log",
  "notify",
+ "num-bigint",
  "once_cell",
  "path-absolutize",
  "rayon",
@@ -1935,6 +2076,11 @@ dependencies = [
  "rustpython-parser",
  "serde",
  "serde_json",
+ "strum",
+ "strum_macros",
+ "test-case",
+ "textwrap",
+ "titlecase",
  "toml",
  "update-informer",
  "walkdir",
@@ -1955,7 +2101,7 @@ dependencies = [
 [[package]]
 name = "rustpython-ast"
 version = "0.1.0"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=4f457893efc381ad5c432576b24bcc7e4a08c641#4f457893efc381ad5c432576b24bcc7e4a08c641"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=1b253a12705f84972cd76e8dc1cdaaccb233e5a5#1b253a12705f84972cd76e8dc1cdaaccb233e5a5"
 dependencies = [
  "num-bigint",
  "rustpython-common",
@@ -1965,7 +2111,7 @@ dependencies = [
 [[package]]
 name = "rustpython-common"
 version = "0.0.0"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=4f457893efc381ad5c432576b24bcc7e4a08c641#4f457893efc381ad5c432576b24bcc7e4a08c641"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=1b253a12705f84972cd76e8dc1cdaaccb233e5a5#1b253a12705f84972cd76e8dc1cdaaccb233e5a5"
 dependencies = [
  "ascii",
  "cfg-if 1.0.0",
@@ -1988,7 +2134,7 @@ dependencies = [
 [[package]]
 name = "rustpython-compiler-core"
 version = "0.1.2"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=4f457893efc381ad5c432576b24bcc7e4a08c641#4f457893efc381ad5c432576b24bcc7e4a08c641"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=1b253a12705f84972cd76e8dc1cdaaccb233e5a5#1b253a12705f84972cd76e8dc1cdaaccb233e5a5"
 dependencies = [
  "bincode",
  "bitflags",
@@ -2005,7 +2151,7 @@ dependencies = [
 [[package]]
 name = "rustpython-parser"
 version = "0.1.2"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=4f457893efc381ad5c432576b24bcc7e4a08c641#4f457893efc381ad5c432576b24bcc7e4a08c641"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=1b253a12705f84972cd76e8dc1cdaaccb233e5a5#1b253a12705f84972cd76e8dc1cdaaccb233e5a5"
 dependencies = [
  "ahash",
  "anyhow",
@@ -2053,6 +2199,12 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
+[[package]]
+name = "scratch"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8132065adcfd6e02db789d9285a0deb2f3fcb04002865ab67d5fb103533898"
+
 [[package]]
 name = "sct"
 version = "0.7.0"
@@ -2091,9 +2243,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.85"
+version = "1.0.86"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e55a28e3aaef9d5ce0506d0a14dbba8054ddc7e499ef522dd8b26859ec9d4a44"
+checksum = "41feea4228a6f1cd09ec7a3593a682276702cd67b5273544757dae23c096f074"
 dependencies = [
  "itoa",
  "ryu",
@@ -2196,6 +2348,12 @@ version = "1.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a507befe795404456341dfab10cef66ead4c041f62b8b11bbb92bffe5d0953e0"
 
+[[package]]
+name = "smawk"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f67ad224767faa3c7d8b6d91985b78e70a1324408abcb1cfcc2be4c06bc06043"
+
 [[package]]
 name = "socket2"
 version = "0.4.7"
@@ -2253,10 +2411,32 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
 [[package]]
-name = "syn"
-version = "1.0.101"
+name = "strum"
+version = "0.24.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e90cde112c4b9690b8cbe810cba9ddd8bc1d7472e2cae317b69e9438c1cba7d2"
+checksum = "063e6045c0e62079840579a7e47a355ae92f60eb74daaf156fb1e84ba164e63f"
+dependencies = [
+ "strum_macros",
+]
+
+[[package]]
+name = "strum_macros"
+version = "0.24.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e385be0d24f186b4ce2f9982191e7101bb737312ad61c1f2f984f34bcf85d59"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "rustversion",
+ "syn",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.102"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3fcd952facd492f9be3ef0d0b7032a6e442ee9b361d4acc2b1d0c4aaa5f613a1"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2320,6 +2500,45 @@ dependencies = [
  "phf_codegen 0.8.0",
 ]
 
+[[package]]
+name = "termtree"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "507e9898683b6c43a9aa55b64259b721b52ba226e0f3779137e50ad114a4c90b"
+
+[[package]]
+name = "test-case"
+version = "2.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "21d6cf5a7dffb3f9dceec8e6b8ca528d9bd71d36c9f074defb548ce161f598c0"
+dependencies = [
+ "test-case-macros",
+]
+
+[[package]]
+name = "test-case-macros"
+version = "2.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e45b7bf6e19353ddd832745c8fcf77a17a93171df7151187f26623f2b75b5b26"
+dependencies = [
+ "cfg-if 1.0.0",
+ "proc-macro-error",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "textwrap"
+version = "0.15.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "949517c0cf1bf4ee812e2e07e08ab448e3ae0d23472aee8a06c985f0c8815b16"
+dependencies = [
+ "smawk",
+ "unicode-linebreak",
+ "unicode-width",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.37"
@@ -2375,6 +2594,17 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cda74da7e1a664f795bb1f8a87ec406fb89a02522cf6e50620d016add6dbbf5c"
 
+[[package]]
+name = "titlecase"
+version = "2.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38397a8cdb017cfeb48bf6c154d6de975ac69ffeed35980fde199d2ee0842042"
+dependencies = [
+ "joinery",
+ "lazy_static",
+ "regex",
+]
+
 [[package]]
 name = "toml"
 version = "0.5.9"
@@ -2472,9 +2702,19 @@ checksum = "099b7128301d285f79ddd55b9a83d5e6b9e97c92e0ea0daebee7263e932de992"
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.4"
+version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dcc811dc4066ac62f84f11307873c4850cb653bfa9b1719cee2bd2204a4bc5dd"
+checksum = "6ceab39d59e4c9499d4e5a8ee0e2735b891bb7308ac83dfb4e80cad195c9f6f3"
+
+[[package]]
+name = "unicode-linebreak"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c5faade31a542b8b35855fff6e8def199853b2da8da256da52f52f1316ee3137"
+dependencies = [
+ "hashbrown",
+ "regex",
+]
 
 [[package]]
 name = "unicode-normalization"
@@ -2485,6 +2725,12 @@ dependencies = [
  "tinyvec",
 ]
 
+[[package]]
+name = "unicode-width"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c0edd1e5b14653f783770bce4a4dabb4a5108a5370a5f5d8cfe8710c361f6c8b"
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.4"
@@ -2568,6 +2814,15 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8e76fae08f03f96e166d2dfda232190638c10e0383841252416f9cfe2ae60e6"
 
+[[package]]
+name = "wait-timeout"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f200f5b12eb75f8c1ed65abd4b2db8a6e1b138a20de009dacee265a2498f3f6"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "waker-fn"
 version = "1.1.0"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.0.60"
+version = "0.0.81"
 edition = "2021"
 
 [lib]
@@ -9,10 +9,8 @@ name = "ruff"
 [dependencies]
 anyhow = { version = "1.0.60" }
 bincode = { version = "1.3.3" }
-cacache = { version = "10.0.1" }
 chrono = { version = "0.4.21" }
 clap = { version = "4.0.1", features = ["derive"] }
-clearscreen = { version = "1.0.10" }
 colored = { version = "2.0.0" }
 common-path = { version = "1.0.0" }
 dirs = { version = "4.0.0" }
@@ -23,21 +21,37 @@ itertools = { version = "0.10.5" }
 libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "32a044c127668df44582f85699358e67803b0d73" }
 log = { version = "0.4.17" }
 notify = { version = "4.0.17" }
+num-bigint = { version = "0.4.3" }
 once_cell = { version = "1.13.1" }
-path-absolutize = { version = "3.0.13", features = ["once_cell_cache"] }
+path-absolutize = { version = "3.0.14", features = ["once_cell_cache", "use_unix_paths_on_wasm"] }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
-rustpython-ast = { features = ["unparse"], git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
-rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
-rustpython-common = { git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
+rustpython-ast = { features = ["unparse"], git = "https://github.com/charliermarsh/RustPython.git", rev = "1b253a12705f84972cd76e8dc1cdaaccb233e5a5" }
+rustpython-common = { git = "https://github.com/charliermarsh/RustPython.git", rev = "1b253a12705f84972cd76e8dc1cdaaccb233e5a5" }
+rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "1b253a12705f84972cd76e8dc1cdaaccb233e5a5" }
 serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
+strum = { version = "0.24.1", features = ["strum_macros"] }
+strum_macros = { version = "0.24.3" }
+textwrap = { version = "0.15.1" }
+titlecase = { version = "2.2.1" }
 toml = { version = "0.5.9" }
 update-informer = { version = "0.5.0", default_features = false, features = ["pypi"], optional = true }
 walkdir = { version = "2.3.2" }
 
+[target.'cfg(not(target_family = "wasm"))'.dependencies]
+cacache = { version = "10.0.1" } # uses async-std
+clearscreen = { version = "1.0.10" } # uses which
+
+# https://docs.rs/getrandom/0.2.7/getrandom/#webassembly-support
+# For (future) wasm-pack support
+[target.'cfg(all(target_family = "wasm", target_os = "unknown"))'.dependencies]
+getrandom = { version = "0.2.7", features = ["js"] }
+
 [dev-dependencies]
+assert_cmd = { version = "2.0.4" }
 insta = { version = "1.19.1", features = ["yaml"] }
+test-case = { version = "2.2.2" }
 
 [features]
 default = ["update-informer"]

README.md

@@ -1,4 +1,4 @@
-# ruff
+# Ruff
 
 [![image](https://img.shields.io/pypi/v/ruff.svg)](https://pypi.python.org/pypi/ruff)
 [![image](https://img.shields.io/pypi/l/ruff.svg)](https://pypi.python.org/pypi/ruff)
@@ -20,17 +20,37 @@ An extremely fast Python linter, written in Rust.
 - 🤝 Python 3.10 compatibility
 - 🛠️ `pyproject.toml` support
 - 📦 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired cache support
-- 🔧 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix)-inspired `--fix` support
-- 👀 [TypeScript](https://www.typescriptlang.org/docs/handbook/configuring-watch.html)-inspired `--watch` support
-- ⚖️ [Near-complete parity](#Parity-with-Flake8) with the built-in Flake8 rule set
+- 🔧 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix)-inspired autofix support (e.g., automatically remove unused imports)
+- 👀 [TypeScript](https://www.typescriptlang.org/docs/handbook/configuring-watch.html)-inspired `--watch` support, for continuous file monitoring
+- ⚖️ [Near-parity](#how-does-ruff-compare-to-flake8) with the built-in Flake8 rule set
+- 🔌 Native re-implementations of popular Flake8 plugins, like [`flake8-docstrings`](https://pypi.org/project/flake8-docstrings/) ([`pydocstyle`](https://pypi.org/project/pydocstyle/))
+
+Ruff aims to be orders of magnitude faster than alternative tools while integrating more
+functionality behind a single, common interface. Ruff can be used to replace Flake8 (plus a variety
+of plugins), [`pydocstyle`](https://pypi.org/project/pydocstyle/), [`yesqa`](https://github.com/asottile/yesqa),
+and even a subset of [`pyupgrade`](https://pypi.org/project/pyupgrade/) and [`autoflake`](https://pypi.org/project/autoflake/)
+all while executing tens or hundreds of times faster than any individual tool.
 
 Read the [launch blog post](https://notes.crmarsh.com/python-tooling-could-be-much-much-faster).
 
-## Installation and usage
+## Table of Contents
+
+1. [Installation and Usage](#installation-and-usage)
+2. [Configuration](#configuration)
+3. [Supported Rules](#supported-rules)
+4. [Editor Integrations](#editor-integrations)
+5. [FAQ](#faq)
+6. [Development](#development)
+7. [Releases](#releases)
+8. [Benchmarks](#benchmarks)
+9. [License](#license)
+10. [Contributing](#contributing)
+
+## Installation and Usage
 
 ### Installation
 
-Available as [ruff](https://pypi.org/project/ruff/) on PyPI:
+Available as [`ruff`](https://pypi.org/project/ruff/) on PyPI:
 
 ```shell
 pip install ruff
@@ -38,7 +58,7 @@ pip install ruff
 
 ### Usage
 
-To run ruff, try any of the following:
+To run Ruff, try any of the following:
 
 ```shell
 ruff path/to/code/to/check.py
@@ -46,27 +66,27 @@ ruff path/to/code/
 ruff path/to/code/*.py
 ```
 
-You can run ruff in `--watch` mode to automatically re-run on-change:
+You can run Ruff in `--watch` mode to automatically re-run on-change:
 
 ```shell
 ruff path/to/code/ --watch
 ```
 
-ruff also works with [pre-commit](https://pre-commit.com):
+Ruff also works with [pre-commit](https://pre-commit.com):
 
 ```yaml
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.48
+    rev: v0.0.81
     hooks:
       - id: lint
 ```
 
 ## Configuration
 
-ruff is configurable both via `pyproject.toml` and the command line.
+Ruff is configurable both via `pyproject.toml` and the command line.
 
-For example, you could configure ruff to only enforce a subset of rules with:
+For example, you could configure Ruff to only enforce a subset of rules with:
 
 ```toml
 [tool.ruff]
@@ -94,6 +114,8 @@ Arguments:
   <FILES>...
 
 Options:
+      --config <CONFIG>
+          Path to the `pyproject.toml` file to use for configuration
   -v, --verbose
           Enable verbose logging
   -q, --quiet
@@ -132,6 +154,8 @@ Options:
           Regular expression matching the name of dummy variables
       --target-version <TARGET_VERSION>
           The minimum Python version that should be supported
+      --stdin-filename <STDIN_FILENAME>
+          The name of the file when passing it through stdin
   -h, --help
           Print help information
   -V, --version
@@ -154,7 +178,7 @@ Exclusions are based on globs, and can be either:
 To omit a lint check entirely, add it to the "ignore" list via `--ignore` or `--extend-ignore`,
 either  on the command-line or in your `project.toml` file.
 
-To ignore an error in-line, ruff uses a `noqa` system similar to [Flake8](https://flake8.pycqa.org/en/3.1.1/user/ignoring-errors.html).
+To ignore an error in-line, Ruff uses a `noqa` system similar to [Flake8](https://flake8.pycqa.org/en/3.1.1/user/ignoring-errors.html).
 To ignore an individual error, add `# noqa: {code}` to the end of the line, like so:
 
 ```python
@@ -178,136 +202,220 @@ Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor i
 """  # noqa: E501
 ```
 
-ruff supports several (experimental) workflows to aid in `noqa` management.
+Ruff supports several workflows to aid in `noqa` management.
 
-First, ruff provides a special error code, `M001`, to enforce that your `noqa` directives are
+First, Ruff provides a special error code, `M001`, to enforce that your `noqa` directives are
 "valid", in that the errors they _say_ they ignore are actually being triggered on that line (and
 thus suppressed). **You can run `ruff /path/to/file.py --extend-select M001` to flag unused `noqa`
 directives.**
 
-Second, ruff can _automatically remove_ unused `noqa` directives via its autofix functionality.
+Second, Ruff can _automatically remove_ unused `noqa` directives via its autofix functionality.
 **You can run `ruff /path/to/file.py --extend-select M001 --fix` to automatically remove unused
 `noqa` directives.**
 
-Third, ruff can _automatically add_ `noqa` directives to all failing lines. This is useful when
-migrating a new codebase to ruff. **You can run `ruff /path/to/file.py --add-noqa` to automatically
+Third, Ruff can _automatically add_ `noqa` directives to all failing lines. This is useful when
+migrating a new codebase to Ruff. **You can run `ruff /path/to/file.py --add-noqa` to automatically
 add `noqa` directives to all failing lines, with the appropriate error codes.**
 
-### Compatibility with Black
+## Supported Rules
 
-ruff is compatible with [Black](https://github.com/psf/black) out-of-the-box, as long as
-the `line-length` setting is consistent between the two.
-
-As a project, ruff is designed to be used alongside Black and, as such, will defer implementing
-stylistic lint rules that are obviated by autoformatting.
-
-### Parity with Flake8
-
-ruff's goal is to achieve feature parity with Flake8 when used (1) without plugins, (2) alongside
-Black, and (3) on Python 3 code.
-
-**Under those conditions, ruff implements 44 out of 60 rules.** (ruff is missing: 14 rules related
-to string `.format` calls, 1 rule related to docstring parsing, and 1 rule related to redefined
-variables.)
-
-ruff also implements some of the most popular Flake8 plugins natively, including:
-
-- [`flake8-builtins`](https://pypi.org/project/flake8-builtins/)
-- [`flake8-super`](https://pypi.org/project/flake8-super/)
-- [`flake8-print`](https://pypi.org/project/flake8-print/)
-- [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/) (partial)
-- [`pyupgrade`](https://pypi.org/project/pyupgrade/) (partial)
-
-Beyond rule-set parity, ruff suffers from the following limitations vis-à-vis Flake8:
-
-1. ruff does not yet support a few Python 3.9 and 3.10 language features, including structural
-   pattern matching and parenthesized context managers.
-2. Flake8 has a plugin architecture and supports writing custom lint rules.
-
-## Rules
-
-The ✅ emoji indicates a rule is enabled by default.
+By default, Ruff enables all `E`, `W`, and `F` error codes, which correspond to those built-in to
+Flake8.
 
 The 🛠 emoji indicates that a rule is automatically fixable by the `--fix` command-line option.
 
-| Code | Name | Message |     |     |
-| ---- | ---- | ------- | --- | --- |
-| E402 | ModuleImportNotAtTopOfFile | Module level import not at top of file | ✅ |  |
-| E501 | LineTooLong | Line too long (89 > 88 characters) | ✅ |  |
-| E711 | NoneComparison | Comparison to `None` should be `cond is None` | ✅ |  |
-| E712 | TrueFalseComparison | Comparison to `True` should be `cond is True` | ✅ |  |
-| E713 | NotInTest | Test for membership should be `not in` | ✅ |  |
-| E714 | NotIsTest | Test for object identity should be `is not` | ✅ |  |
-| E721 | TypeComparison | Do not compare types, use `isinstance()` | ✅ |  |
-| E722 | DoNotUseBareExcept | Do not use bare `except` | ✅ |  |
-| E731 | DoNotAssignLambda | Do not assign a lambda expression, use a def | ✅ |  |
-| E741 | AmbiguousVariableName | Ambiguous variable name: `...` | ✅ |  |
-| E742 | AmbiguousClassName | Ambiguous class name: `...` | ✅ |  |
-| E743 | AmbiguousFunctionName | Ambiguous function name: `...` | ✅ |  |
-| E902 | IOError | IOError: `...` | ✅ |  |
-| E999 | SyntaxError | SyntaxError: `...` | ✅ |  |
-| F401 | UnusedImport | `...` imported but unused | ✅ | 🛠 |
-| F402 | ImportShadowedByLoopVar | Import `...` from line 1 shadowed by loop variable | ✅ |  |
-| F403 | ImportStarUsed | `from ... import *` used; unable to detect undefined names | ✅ |  |
-| F404 | LateFutureImport | `from __future__` imports must occur at the beginning of the file | ✅ |  |
-| F405 | ImportStarUsage | `...` may be undefined, or defined from star imports: `...` | ✅ |  |
-| F406 | ImportStarNotPermitted | `from ... import *` only allowed at module level | ✅ |  |
-| F407 | FutureFeatureNotDefined | Future feature `...` is not defined | ✅ |  |
-| F541 | FStringMissingPlaceholders | f-string without any placeholders | ✅ |  |
-| F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated | ✅ |  |
-| F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated | ✅ |  |
-| F621 | ExpressionsInStarAssignment | Too many expressions in star-unpacking assignment | ✅ |  |
-| F622 | TwoStarredExpressions | Two starred expressions in assignment | ✅ |  |
-| F631 | AssertTuple | Assert test is a non-empty tuple, which is always `True` | ✅ |  |
-| F632 | IsLiteral | Use `==` and `!=` to compare constant literals | ✅ |  |
-| F633 | InvalidPrintSyntax | Use of `>>` is invalid with `print` function | ✅ |  |
-| F634 | IfTuple | If test is a tuple, which is always `True` | ✅ |  |
-| F701 | BreakOutsideLoop | `break` outside loop | ✅ |  |
-| F702 | ContinueOutsideLoop | `continue` not properly in loop | ✅ |  |
-| F704 | YieldOutsideFunction | `yield` or `yield from` statement outside of a function/method | ✅ |  |
-| F706 | ReturnOutsideFunction | `return` statement outside of a function/method | ✅ |  |
-| F707 | DefaultExceptNotLast | An `except:` block as not the last exception handler | ✅ |  |
-| F722 | ForwardAnnotationSyntaxError | Syntax error in forward annotation: `...` | ✅ |  |
-| F821 | UndefinedName | Undefined name `...` | ✅ |  |
-| F822 | UndefinedExport | Undefined name `...` in `__all__` | ✅ |  |
-| F823 | UndefinedLocal | Local variable `...` referenced before assignment | ✅ |  |
-| F831 | DuplicateArgumentName | Duplicate argument name in function definition | ✅ |  |
-| F841 | UnusedVariable | Local variable `...` is assigned to but never used | ✅ |  |
-| F901 | RaiseNotImplemented | `raise NotImplemented` should be `raise NotImplementedError` | ✅ |  |
-| A001 | BuiltinVariableShadowing | Variable `...` is shadowing a python builtin |  |  |
-| A002 | BuiltinArgumentShadowing | Argument `...` is shadowing a python builtin |  |  |
-| A003 | BuiltinAttributeShadowing | Class attribute `...` is shadowing a python builtin |  |  |
-| C400 | UnnecessaryGeneratorList | Unnecessary generator - rewrite as a list comprehension |  |  |
-| C401 | UnnecessaryGeneratorSet | Unnecessary generator - rewrite as a set comprehension |  |  |
-| C403 | UnnecessaryListComprehensionSet | Unnecessary list comprehension - rewrite as a set comprehension |  |  |
-| C404 | UnnecessaryListComprehensionDict | Unnecessary list comprehension - rewrite as a dict comprehension |  |  |
-| SPR001 | SuperCallWithParameters | Use `super()` instead of `super(__class__, self)` |  | 🛠 |
-| T201 | PrintFound | `print` found |  | 🛠 |
-| T203 | PPrintFound | `pprint` found |  | 🛠 |
-| U001 | UselessMetaclassType | `__metaclass__ = type` is implied |  | 🛠 |
-| U002 | UnnecessaryAbspath | `abspath(__file__)` is unnecessary in Python 3.9 and later |  | 🛠 |
-| U003 | TypeOfPrimitive | Use `str` instead of `type(...)` |  | 🛠 |
-| U004 | UselessObjectInheritance | Class `...` inherits from object |  | 🛠 |
-| U005 | NoAssertEquals | `assertEquals` is deprecated, use `assertEqual` instead |  | 🛠 |
-| M001 | UnusedNOQA | Unused `noqa` directive |  | 🛠 |
+### Pyflakes
 
-## Integrations
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| F401 | UnusedImport | `...` imported but unused | 🛠 |
+| F402 | ImportShadowedByLoopVar | Import `...` from line 1 shadowed by loop variable |  |
+| F403 | ImportStarUsed | `from ... import *` used; unable to detect undefined names |  |
+| F404 | LateFutureImport | `from __future__` imports must occur at the beginning of the file |  |
+| F405 | ImportStarUsage | `...` may be undefined, or defined from star imports: `...` |  |
+| F406 | ImportStarNotPermitted | `from ... import *` only allowed at module level |  |
+| F407 | FutureFeatureNotDefined | Future feature `...` is not defined |  |
+| F541 | FStringMissingPlaceholders | f-string without any placeholders |  |
+| F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated |  |
+| F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated |  |
+| F621 | ExpressionsInStarAssignment | Too many expressions in star-unpacking assignment |  |
+| F622 | TwoStarredExpressions | Two starred expressions in assignment |  |
+| F631 | AssertTuple | Assert test is a non-empty tuple, which is always `True` |  |
+| F632 | IsLiteral | Use `==` and `!=` to compare constant literals |  |
+| F633 | InvalidPrintSyntax | Use of `>>` is invalid with `print` function |  |
+| F634 | IfTuple | If test is a tuple, which is always `True` |  |
+| F701 | BreakOutsideLoop | `break` outside loop |  |
+| F702 | ContinueOutsideLoop | `continue` not properly in loop |  |
+| F704 | YieldOutsideFunction | `yield` or `yield from` statement outside of a function/method |  |
+| F706 | ReturnOutsideFunction | `return` statement outside of a function/method |  |
+| F707 | DefaultExceptNotLast | An `except:` block as not the last exception handler |  |
+| F722 | ForwardAnnotationSyntaxError | Syntax error in forward annotation: `...` |  |
+| F821 | UndefinedName | Undefined name `...` |  |
+| F822 | UndefinedExport | Undefined name `...` in `__all__` |  |
+| F823 | UndefinedLocal | Local variable `...` referenced before assignment |  |
+| F831 | DuplicateArgumentName | Duplicate argument name in function definition |  |
+| F841 | UnusedVariable | Local variable `...` is assigned to but never used |  |
+| F901 | RaiseNotImplemented | `raise NotImplemented` should be `raise NotImplementedError` |  |
+
+### pycodestyle
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| E402 | ModuleImportNotAtTopOfFile | Module level import not at top of file |  |
+| E501 | LineTooLong | Line too long (89 > 88 characters) |  |
+| E711 | NoneComparison | Comparison to `None` should be `cond is None` |  |
+| E712 | TrueFalseComparison | Comparison to `True` should be `cond is True` |  |
+| E713 | NotInTest | Test for membership should be `not in` |  |
+| E714 | NotIsTest | Test for object identity should be `is not` |  |
+| E721 | TypeComparison | Do not compare types, use `isinstance()` |  |
+| E722 | DoNotUseBareExcept | Do not use bare `except` |  |
+| E731 | DoNotAssignLambda | Do not assign a lambda expression, use a def |  |
+| E741 | AmbiguousVariableName | Ambiguous variable name: `...` |  |
+| E742 | AmbiguousClassName | Ambiguous class name: `...` |  |
+| E743 | AmbiguousFunctionName | Ambiguous function name: `...` |  |
+| E902 | IOError | IOError: `...` |  |
+| E999 | SyntaxError | SyntaxError: `...` |  |
+| W292 | NoNewLineAtEndOfFile | No newline at end of file |  |
+
+### pydocstyle
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| D100 | PublicModule | Missing docstring in public module |  |
+| D101 | PublicClass | Missing docstring in public class |  |
+| D102 | PublicMethod | Missing docstring in public method |  |
+| D103 | PublicFunction | Missing docstring in public function |  |
+| D104 | PublicPackage | Missing docstring in public package |  |
+| D105 | MagicMethod | Missing docstring in magic method |  |
+| D106 | PublicNestedClass | Missing docstring in public nested class |  |
+| D107 | PublicInit | Missing docstring in `__init__` |  |
+| D200 | FitsOnOneLine | One-line docstring should fit on one line |  |
+| D201 | NoBlankLineBeforeFunction | No blank lines allowed before function docstring (found 1) | 🛠 |
+| D202 | NoBlankLineAfterFunction | No blank lines allowed after function docstring (found 1) | 🛠 |
+| D203 | OneBlankLineBeforeClass | 1 blank line required before class docstring | 🛠 |
+| D204 | OneBlankLineAfterClass | 1 blank line required after class docstring | 🛠 |
+| D205 | BlankLineAfterSummary | 1 blank line required between summary line and description | 🛠 |
+| D206 | IndentWithSpaces | Docstring should be indented with spaces, not tabs |  |
+| D207 | NoUnderIndentation | Docstring is under-indented | 🛠 |
+| D208 | NoOverIndentation | Docstring is over-indented | 🛠 |
+| D209 | NewLineAfterLastParagraph | Multi-line docstring closing quotes should be on a separate line | 🛠 |
+| D210 | NoSurroundingWhitespace | No whitespaces allowed surrounding docstring text | 🛠 |
+| D211 | NoBlankLineBeforeClass | No blank lines allowed before class docstring | 🛠 |
+| D212 | MultiLineSummaryFirstLine | Multi-line docstring summary should start at the first line |  |
+| D213 | MultiLineSummarySecondLine | Multi-line docstring summary should start at the second line |  |
+| D214 | SectionNotOverIndented | Section is over-indented ("Returns") | 🛠 |
+| D215 | SectionUnderlineNotOverIndented | Section underline is over-indented ("Returns") | 🛠 |
+| D300 | UsesTripleQuotes | Use """triple double quotes""" |  |
+| D400 | EndsInPeriod | First line should end with a period |  |
+| D402 | NoSignature | First line should not be the function's 'signature' |  |
+| D403 | FirstLineCapitalized | First word of the first line should be properly capitalized |  |
+| D404 | NoThisPrefix | First word of the docstring should not be `This` |  |
+| D405 | CapitalizeSectionName | Section name should be properly capitalized ("returns") | 🛠 |
+| D406 | NewLineAfterSectionName | Section name should end with a newline ("Returns") | 🛠 |
+| D407 | DashedUnderlineAfterSection | Missing dashed underline after section ("Returns") | 🛠 |
+| D408 | SectionUnderlineAfterName | Section underline should be in the line following the section's name ("Returns") |  |
+| D409 | SectionUnderlineMatchesSectionLength | Section underline should match the length of its name ("Returns") | 🛠 |
+| D410 | BlankLineAfterSection | Missing blank line after section ("Returns") | 🛠 |
+| D411 | BlankLineBeforeSection | Missing blank line before section ("Returns") | 🛠 |
+| D412 | NoBlankLinesBetweenHeaderAndContent | No blank lines allowed between a section header and its content ("Returns") | 🛠 |
+| D413 | BlankLineAfterLastSection | Missing blank line after last section ("Returns") | 🛠 |
+| D414 | NonEmptySection | Section has no content ("Returns") |  |
+| D415 | EndsInPunctuation | First line should end with a period, question mark, or exclamation point |  |
+| D416 | SectionNameEndsInColon | Section name should end with a colon ("Returns") | 🛠 |
+| D417 | DocumentAllArguments | Missing argument descriptions in the docstring: `x`, `y` |  |
+| D418 | SkipDocstring | Function decorated with @overload shouldn't contain a docstring |  |
+| D419 | NonEmpty | Docstring is empty |  |
+
+### pyupgrade
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| U001 | UselessMetaclassType | `__metaclass__ = type` is implied | 🛠 |
+| U002 | UnnecessaryAbspath | `abspath(__file__)` is unnecessary in Python 3.9 and later | 🛠 |
+| U003 | TypeOfPrimitive | Use `str` instead of `type(...)` | 🛠 |
+| U004 | UselessObjectInheritance | Class `...` inherits from object | 🛠 |
+| U005 | DeprecatedUnittestAlias | `assertEquals` is deprecated, use `assertEqual` instead | 🛠 |
+| U006 | UsePEP585Annotation | Use `list` instead of `List` for type annotations | 🛠 |
+| U007 | UsePEP604Annotation | Use `X \| Y` for type annotations | 🛠 |
+| U008 | SuperCallWithParameters | Use `super()` instead of `super(__class__, self)` | 🛠 |
+
+### pep8-naming
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| N801 | InvalidClassName | Class name `...` should use CapWords convention  |  |
+| N802 | InvalidFunctionName | Function name `...` should be lowercase |  |
+| N803 | InvalidArgumentName | Argument name `...` should be lowercase |  |
+| N804 | InvalidFirstArgumentNameForClassMethod | First argument of a class method should be named `cls` |  |
+| N805 | InvalidFirstArgumentNameForMethod | First argument of a method should be named `self` |  |
+
+### flake8-comprehensions
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| C400 | UnnecessaryGeneratorList | Unnecessary generator (rewrite as a `list` comprehension) |  |
+| C401 | UnnecessaryGeneratorSet | Unnecessary generator (rewrite as a `set` comprehension) |  |
+| C402 | UnnecessaryGeneratorDict | Unnecessary generator (rewrite as a `dict` comprehension) |  |
+| C403 | UnnecessaryListComprehensionSet | Unnecessary `list` comprehension (rewrite as a `set` comprehension) |  |
+| C404 | UnnecessaryListComprehensionDict | Unnecessary `list` comprehension (rewrite as a `dict` comprehension) |  |
+| C405 | UnnecessaryLiteralSet | Unnecessary `(list\|tuple)` literal (rewrite as a `set` literal) |  |
+| C406 | UnnecessaryLiteralDict | Unnecessary `(list\|tuple)` literal (rewrite as a `dict` literal) |  |
+| C408 | UnnecessaryCollectionCall | Unnecessary `(dict\|list\|tuple)` call (rewrite as a literal) |  |
+| C409 | UnnecessaryLiteralWithinTupleCall | Unnecessary `(list\|tuple)` literal passed to `tuple()` (remove the outer call to `tuple()`) |  |
+| C410 | UnnecessaryLiteralWithinListCall | Unnecessary `(list\|tuple)` literal passed to `list()` (rewrite as a `list` literal) |  |
+| C411 | UnnecessaryListCall | Unnecessary `list` call (remove the outer call to `list()`) |  |
+| C413 | UnnecessaryCallAroundSorted | Unnecessary `(list\|reversed)` call around `sorted()` |  |
+| C414 | UnnecessaryDoubleCastOrProcess | Unnecessary `(list\|reversed\|set\|sorted\|tuple)` call within `(list\|set\|sorted\|tuple)()` |  |
+| C415 | UnnecessarySubscriptReversal | Unnecessary subscript reversal of iterable within `(reversed\|set\|sorted)()` |  |
+| C416 | UnnecessaryComprehension |  Unnecessary `(list\|set)` comprehension (rewrite using `(list\|set)()`) |  |
+| C417 | UnnecessaryMap | Unnecessary `map` usage (rewrite using a `(list\|set\|dict)` comprehension) |  |
+
+### flake8-bugbear
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| B011 | DoNotAssertFalse | Do not `assert False` (`python -O` removes these calls), raise `AssertionError()` | 🛠 |
+| B014 | DuplicateHandlerException | Exception handler with duplicate exception: `ValueError` | 🛠 |
+| B025 | DuplicateTryBlockException | try-except block with duplicate exception `Exception` |  |
+
+### flake8-builtins
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| A001 | BuiltinVariableShadowing | Variable `...` is shadowing a python builtin |  |
+| A002 | BuiltinArgumentShadowing | Argument `...` is shadowing a python builtin |  |
+| A003 | BuiltinAttributeShadowing | Class attribute `...` is shadowing a python builtin |  |
+
+### flake8-print
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| T201 | PrintFound | `print` found | 🛠 |
+| T203 | PPrintFound | `pprint` found | 🛠 |
+
+### Meta rules
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| M001 | UnusedNOQA | Unused `noqa` directive | 🛠 |
+
+## Editor Integrations
 
 ### PyCharm
 
-ruff can be installed as an [External Tool](https://www.jetbrains.com/help/pycharm/configuring-third-party-tools.html)
+Ruff can be installed as an [External Tool](https://www.jetbrains.com/help/pycharm/configuring-third-party-tools.html)
 in PyCharm. Open the Preferences pane, then navigate to "Tools", then "External Tools". From there,
 add a new tool with the following configuration:
 
-![Install ruff as an External Tool](https://user-images.githubusercontent.com/1309177/193155720-336e43f0-1a8d-46b4-bc12-e60f9ae01f7e.png)
+![Install Ruff as an External Tool](https://user-images.githubusercontent.com/1309177/193155720-336e43f0-1a8d-46b4-bc12-e60f9ae01f7e.png)
 
-ruff should then appear as a runnable action:
+Ruff should then appear as a runnable action:
 
-![ruff as a runnable action](https://user-images.githubusercontent.com/1309177/193156026-732b0aaf-3dd9-4549-9b4d-2de6d2168a33.png)
+![Ruff as a runnable action](https://user-images.githubusercontent.com/1309177/193156026-732b0aaf-3dd9-4549-9b4d-2de6d2168a33.png)
 
 ### GitHub Actions
 
-GitHub Actions has everything you need to run ruff out-of-the-box:
+GitHub Actions has everything you need to run Ruff out-of-the-box:
 
 ```yaml
 name: CI
@@ -316,22 +424,184 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Install Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: "3.10"
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
           pip install ruff
-      - name: Run ruff
+      - name: Run Ruff
         run: ruff .
 ```
 
+## FAQ
+
+### Is Ruff compatible with Black?
+
+Yes. Ruff is compatible with [Black](https://github.com/psf/black) out-of-the-box, as long as
+the `line-length` setting is consistent between the two.
+
+As a project, Ruff is designed to be used alongside Black and, as such, will defer implementing
+stylistic lint rules that are obviated by autoformatting.
+
+### How does Ruff compare to Flake8?
+
+Ruff can be used as a (near) drop-in replacement for Flake8 when used (1) without or with a small
+number of plugins, (2) alongside Black, and (3) on Python 3 code.
+
+Under those conditions Ruff is missing 14 rules related to string `.format` calls, 1 rule related
+to docstring parsing, and 1 rule related to redefined variables.
+
+Ruff re-implements some of the most popular Flake8 plugins and related code quality tools natively,
+including:
+
+- [`pydocstyle`](https://pypi.org/project/pydocstyle/)
+- [`yesqa`](https://github.com/asottile/yesqa)
+- [`flake8-docstrings`](https://pypi.org/project/flake8-docstrings/)
+- [`flake8-builtins`](https://pypi.org/project/flake8-builtins/)
+- [`flake8-super`](https://pypi.org/project/flake8-super/)
+- [`flake8-print`](https://pypi.org/project/flake8-print/)
+- [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/)
+- [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (3/32)
+- [`pyupgrade`](https://pypi.org/project/pyupgrade/) (8/34)
+- [`autoflake`](https://pypi.org/project/autoflake/) (1/7)
+
+Beyond rule-set parity, Ruff suffers from the following limitations vis-à-vis Flake8:
+
+1. Ruff does not yet support a few Python 3.9 and 3.10 language features, including structural
+   pattern matching and parenthesized context managers.
+2. Flake8 has a plugin architecture and supports writing custom lint rules. (To date, popular Flake8
+   plugins have been re-implemented within Ruff directly.)
+
+### Which tools does Ruff replace?
+
+Today, Ruff can be used to replace Flake8 when used with any of the following plugins:
+
+- [`flake8-docstrings`](https://pypi.org/project/flake8-docstrings/)
+- [`flake8-builtins`](https://pypi.org/project/flake8-builtins/)
+- [`flake8-super`](https://pypi.org/project/flake8-super/)
+- [`flake8-print`](https://pypi.org/project/flake8-print/)
+- [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/)
+- [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (3/32)
+
+Ruff also implements the functionality that you get from [`yesqa`](https://github.com/asottile/yesqa),
+and a subset of the rules implemented in [`pyupgrade`](https://pypi.org/project/pyupgrade/) (8/34).
+
+If you're looking to use Ruff, but rely on an unsupported Flake8 plugin, free to file an Issue.
+
+### Do I need to install Rust to use Ruff?
+
+Nope! Ruff is available as [`ruff`](https://pypi.org/project/ruff/) on PyPI:
+
+```shell
+pip install ruff
+```
+
+Ruff ships with wheels for all major platforms, which enables `pip` to install Ruff without relying
+on Rust at all.
+
+### Can I write my own plugins for Ruff?
+
+Ruff does not yet support third-party plugins, though a plugin system is within-scope for the
+project. See [#283](https://github.com/charliermarsh/ruff/issues/2830) for more.
+
+### Does Ruff support NumPy- or Google-style docstrings?
+
+Yes! To enable a specific docstring convention, start by enabling all `pydocstyle` error codes, and
+then selectively disabling based on your [preferred convention](https://www.pydocstyle.org/en/latest/error_codes.html#default-conventions).
+
+For example, if you're coming from `flake8-docstrings`, the following configuration is equivalent to
+`--docstring-convention numpy`:
+
+```toml
+[tool.ruff]
+extend-select = [
+    "D100",
+    "D101",
+    "D102",
+    "D103",
+    "D104",
+    "D105",
+    "D106",
+    "D200",
+    "D201",
+    "D202",
+    "D204",
+    "D205",
+    "D206",
+    "D207",
+    "D208",
+    "D209",
+    "D210",
+    "D211",
+    "D214",
+    "D215",
+    "D300",
+    "D400",
+    "D402",
+    "D403",
+    "D404",
+    "D405",
+    "D406",
+    "D407",
+    "D408",
+    "D409",
+    "D410",
+    "D411",
+    "D412",
+    "D413",
+    "D418",
+    "D419",
+]
+```
+
+Similarly, the following is equivalent to `--docstring-convention google`:
+
+```toml
+[tool.ruff]
+extend-select = [
+    "D100",
+    "D101",
+    "D102",
+    "D103",
+    "D104",
+    "D105",
+    "D106",
+    "D107",
+    "D200",
+    "D201",
+    "D202",
+    "D205",
+    "D206",
+    "D207",
+    "D208",
+    "D209",
+    "D210",
+    "D211",
+    "D212",
+    "D214",
+    "D300",
+    "D402",
+    "D403",
+    "D405",
+    "D410",
+    "D411",
+    "D412",
+    "D414",
+    "D415",
+    "D416",
+    "D417",
+    "D418",
+    "D419",
+]
+```
+
 ## Development
 
-ruff is written in Rust (1.63.0). You'll need to install the [Rust toolchain](https://www.rust-lang.org/tools/install)
+Ruff is written in Rust (1.63.0). You'll need to install the [Rust toolchain](https://www.rust-lang.org/tools/install)
 for development.
 
 Assuming you have `cargo` installed, you can run:
@@ -343,13 +613,13 @@ cargo clippy
 cargo test
 ```
 
-## Deployment
+## Releases
 
-ruff is distributed on [PyPI](https://pypi.org/project/ruff/), and published via [`maturin`](https://github.com/PyO3/maturin).
+Ruff is distributed on [PyPI](https://pypi.org/project/ruff/), and published via [`maturin`](https://github.com/PyO3/maturin).
 
 See: `.github/workflows/release.yaml`.
 
-## Benchmarking
+## Benchmarks
 
 First, clone [CPython](https://github.com/python/cpython). It's a large and diverse Python codebase,
 which makes it a good target for benchmarking.
@@ -426,9 +696,9 @@ hyperfine --ignore-failure --warmup 5 \
 
 In order, these evaluate:
 
-- ruff
+- Ruff
 - Pylint
-- PyFlakes
+- Pyflakes
 - autoflake
 - pycodestyle
 - Flake8

examples/generate_rules_table.rs

@@ -1,27 +1,29 @@
-/// Generate a Markdown-compatible table of supported lint rules.
-use ruff::checks::{CheckCode, ALL_CHECK_CODES, DEFAULT_CHECK_CODES};
+//! Generate a Markdown-compatible table of supported lint rules.
+
+use strum::IntoEnumIterator;
+
+use ruff::checks::{CheckCategory, CheckCode};
 
 fn main() {
-    let mut check_codes: Vec<CheckCode> = ALL_CHECK_CODES.to_vec();
-    check_codes.sort();
+    for check_category in CheckCategory::iter() {
+        println!("### {}", check_category.title());
+        println!();
 
-    println!("| Code | Name | Message |     |     |");
-    println!("| ---- | ---- | ------- | --- | --- |");
-    for check_code in check_codes {
-        let check_kind = check_code.kind();
-        let default_token = if DEFAULT_CHECK_CODES.contains(&check_code) {
-            "✅"
-        } else {
-            ""
-        };
-        let fix_token = if check_kind.fixable() { "🛠" } else { "" };
-        println!(
-            "| {} | {} | {} | {} | {} |",
-            check_kind.code().as_str(),
-            check_kind.name(),
-            check_kind.body(),
-            default_token,
-            fix_token
-        );
+        println!("| Code | Name | Message | Fix |");
+        println!("| ---- | ---- | ------- | --- |");
+        for check_code in CheckCode::iter() {
+            if check_code.category() == check_category {
+                let check_kind = check_code.kind();
+                let fix_token = if check_kind.fixable() { "🛠" } else { "" };
+                println!(
+                    "| {} | {} | {} | {} |",
+                    check_kind.code().as_ref(),
+                    check_kind.as_ref(),
+                    check_kind.body().replace("|", r"\|"),
+                    fix_token
+                );
+            }
+        }
+        println!();
     }
 }

examples/print_ast.rs

@@ -1,4 +1,5 @@
-/// Print the AST for a given Python file.
+//! Print the AST for a given Python file.
+
 use std::path::PathBuf;
 
 use anyhow::Result;

examples/print_tokens.rs

@@ -1,4 +1,5 @@
-/// Print the token stream for a given Python file.
+//! Print the token stream for a given Python file.
+
 use std::path::PathBuf;
 
 use anyhow::Result;

resources/test/fixtures/B011.py

@@ -0,0 +1,10 @@
+"""
+Should emit:
+B011 - on line 8
+B011 - on line 10
+"""
+
+assert 1 != 2
+assert False
+assert 1 != 2, "message"
+assert False, "message"

resources/test/fixtures/B014.py

@@ -0,0 +1,76 @@
+"""
+Should emit:
+B014 - on lines 11, 17, 28, 42, 49, 56, and 74.
+"""
+
+import binascii
+import re
+
+try:
+    pass
+except (Exception, TypeError):
+    # TypeError is a subclass of Exception, so it doesn't add anything
+    pass
+
+try:
+    pass
+except (OSError, OSError) as err:
+    # Duplicate exception types are useless
+    pass
+
+
+class MyError(Exception):
+    pass
+
+
+try:
+    pass
+except (MyError, MyError):
+    # Detect duplicate non-builtin errors
+    pass
+
+
+try:
+    pass
+except (MyError, Exception) as e:
+    # Don't assume that we're all subclasses of Exception
+    pass
+
+
+try:
+    pass
+except (MyError, BaseException) as e:
+    # But we *can* assume that everything is a subclass of BaseException
+    pass
+
+
+try:
+    pass
+except (re.error, re.error):
+    # Duplicate exception types as attributes
+    pass
+
+
+try:
+    pass
+except (IOError, EnvironmentError, OSError):
+    # Detect if a primary exception and any its aliases are present.
+    #
+    # Since Python 3.3, IOError, EnvironmentError, WindowsError, mmap.error,
+    # socket.error and select.error are aliases of OSError. See PEP 3151 for
+    # more info.
+    pass
+
+
+try:
+    pass
+except (MyException, NotImplemented):
+    # NotImplemented is not an exception, let's not crash on it.
+    pass
+
+
+try:
+    pass
+except (ValueError, binascii.Error):
+    # binascii.Error is a subclass of ValueError.
+    pass

resources/test/fixtures/B025.py

@@ -0,0 +1,38 @@
+"""
+Should emit:
+B025 - on lines 15, 22, 31
+"""
+
+import pickle
+
+try:
+    a = 1
+except ValueError:
+    a = 2
+finally:
+    a = 3
+
+try:
+    a = 1
+except ValueError:
+    a = 2
+except ValueError:
+    a = 2
+
+try:
+    a = 1
+except pickle.PickleError:
+    a = 2
+except ValueError:
+    a = 2
+except pickle.PickleError:
+    a = 2
+
+try:
+    a = 1
+except (ValueError, TypeError):
+    a = 2
+except ValueError:
+    a = 2
+except (OSError, TypeError):
+    a = 2

resources/test/fixtures/C402.py

@@ -0,0 +1 @@
+d = dict((x, x) for x in range(3))

resources/test/fixtures/C405.py

@@ -0,0 +1,5 @@
+s1 = set([1, 2])
+s2 = set((1, 2))
+s3 = set([])
+s4 = set(())
+s5 = set()

resources/test/fixtures/C406.py

@@ -0,0 +1,5 @@
+d1 = dict([(1, 2)])
+d2 = dict(((1, 2),))
+d3 = dict([])
+d4 = dict(())
+d5 = dict()

resources/test/fixtures/C408.py

@@ -0,0 +1,5 @@
+t = tuple()
+l = list()
+d1 = dict()
+d2 = dict(a=1)
+d3 = dict(**d2)

resources/test/fixtures/C409.py

@@ -0,0 +1,3 @@
+t1 = tuple([1, 2])
+t2 = tuple((1, 2))
+t3 = tuple([])

resources/test/fixtures/C410.py

@@ -0,0 +1,4 @@
+l1 = list([1, 2])
+l2 = list((1, 2))
+l3 = list([])
+l4 = list(())

resources/test/fixtures/C411.py

@@ -0,0 +1,2 @@
+x = [1, 2, 3]
+list([i for i in x])

resources/test/fixtures/C413.py

@@ -0,0 +1,4 @@
+x = [2, 3, 1]
+list(sorted(x))
+reversed(sorted(x))
+reversed(sorted(x, reverse=True))

resources/test/fixtures/C414.py

@@ -0,0 +1,14 @@
+x = [1, 2, 3]
+list(list(x))
+list(tuple(x))
+tuple(list(x))
+tuple(tuple(x))
+set(set(x))
+set(list(x))
+set(tuple(x))
+set(sorted(x))
+set(reversed(x))
+sorted(list(x))
+sorted(tuple(x))
+sorted(sorted(x))
+sorted(reversed(x))

resources/test/fixtures/C415.py

@@ -0,0 +1,9 @@
+lst = [2, 1, 3]
+a = set(lst[::-1])
+b = reversed(lst[::-1])
+c = sorted(lst[::-1])
+d = sorted(lst[::-1], reverse=True)
+e = set(lst[2:-1])
+f = set(lst[:1:-1])
+g = set(lst[::1])
+h = set(lst[::-2])

resources/test/fixtures/C416.py

@@ -0,0 +1,6 @@
+x = [1, 2, 3]
+[i for i in x]
+{i for i in x}
+
+[i for i in x if i > 1]
+[i for i in x for j in x]

resources/test/fixtures/C417.py

@@ -0,0 +1,6 @@
+nums = [1, 2, 3]
+map(lambda x: x + 1, nums)
+map(lambda x: str(x), nums)
+list(map(lambda x: x * 2, nums))
+set(map(lambda x: x % 2 == 0, nums))
+dict(map(lambda v: (v, v**2), nums))

resources/test/fixtures/D.py

@@ -0,0 +1,534 @@
+# No docstring, so we can test D100
+from functools import wraps
+import os
+from .expected import Expectation
+from typing import overload
+
+
+expectation = Expectation()
+expect = expectation.expect
+
+expect('class_', 'D101: Missing docstring in public class')
+
+
+class class_:
+
+    expect('meta', 'D419: Docstring is empty')
+
+    class meta:
+        """"""
+
+    @expect('D102: Missing docstring in public method')
+    def method(self=None):
+        pass
+
+    def _ok_since_private(self=None):
+        pass
+
+    @overload
+    def overloaded_method(self, a: int) -> str:
+        ...
+
+    @overload
+    def overloaded_method(self, a: str) -> str:
+        """Foo bar documentation."""
+        ...
+
+    def overloaded_method(a):
+        """Foo bar documentation."""
+        return str(a)
+
+    expect('overloaded_method',
+           "D418: Function/ Method decorated with @overload"
+           " shouldn't contain a docstring")
+
+    @property
+    def foo(self):
+        """The foo of the thing, which isn't in imperitive mood."""
+        return "hello"
+
+    @expect('D102: Missing docstring in public method')
+    def __new__(self=None):
+        pass
+
+    @expect('D107: Missing docstring in __init__')
+    def __init__(self=None):
+        pass
+
+    @expect('D105: Missing docstring in magic method')
+    def __str__(self=None):
+        pass
+
+    @expect('D102: Missing docstring in public method')
+    def __call__(self=None, x=None, y=None, z=None):
+        pass
+
+
+@expect('D419: Docstring is empty')
+def function():
+    """ """
+    def ok_since_nested():
+        pass
+
+    @expect('D419: Docstring is empty')
+    def nested():
+        ''
+
+
+def function_with_nesting():
+    """Foo bar documentation."""
+    @overload
+    def nested_overloaded_func(a: int) -> str:
+        ...
+
+    @overload
+    def nested_overloaded_func(a: str) -> str:
+        """Foo bar documentation."""
+        ...
+
+    def nested_overloaded_func(a):
+        """Foo bar documentation."""
+        return str(a)
+
+
+expect('nested_overloaded_func',
+       "D418: Function/ Method decorated with @overload"
+       " shouldn't contain a docstring")
+
+
+@overload
+def overloaded_func(a: int) -> str:
+    ...
+
+
+@overload
+def overloaded_func(a: str) -> str:
+    """Foo bar documentation."""
+    ...
+
+
+def overloaded_func(a):
+    """Foo bar documentation."""
+    return str(a)
+
+
+expect('overloaded_func',
+       "D418: Function/ Method decorated with @overload"
+       " shouldn't contain a docstring")
+
+
+@expect('D200: One-line docstring should fit on one line with quotes '
+        '(found 3)')
+@expect('D212: Multi-line docstring summary should start at the first line')
+def asdlkfasd():
+    """
+    Wrong.
+    """
+
+
+@expect('D201: No blank lines allowed before function docstring (found 1)')
+def leading_space():
+
+    """Leading space."""
+
+
+@expect('D202: No blank lines allowed after function docstring (found 1)')
+def trailing_space():
+    """Leading space."""
+
+    pass
+
+
+@expect('D201: No blank lines allowed before function docstring (found 1)')
+@expect('D202: No blank lines allowed after function docstring (found 1)')
+def trailing_and_leading_space():
+
+    """Trailing and leading space."""
+
+    pass
+
+
+expect('LeadingSpaceMissing',
+       'D203: 1 blank line required before class docstring (found 0)')
+
+
+class LeadingSpaceMissing:
+    """Leading space missing."""
+
+
+expect('WithLeadingSpace',
+       'D211: No blank lines allowed before class docstring (found 1)')
+
+
+class WithLeadingSpace:
+
+    """With leading space."""
+
+
+expect('TrailingSpace',
+       'D204: 1 blank line required after class docstring (found 0)')
+expect('TrailingSpace',
+       'D211: No blank lines allowed before class docstring (found 1)')
+
+
+class TrailingSpace:
+
+    """TrailingSpace."""
+    pass
+
+
+expect('LeadingAndTrailingSpaceMissing',
+       'D203: 1 blank line required before class docstring (found 0)')
+expect('LeadingAndTrailingSpaceMissing',
+       'D204: 1 blank line required after class docstring (found 0)')
+
+
+class LeadingAndTrailingSpaceMissing:
+    """Leading and trailing space missing."""
+    pass
+
+
+@expect('D205: 1 blank line required between summary line and description '
+        '(found 0)')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multi_line_zero_separating_blanks():
+    """Summary.
+    Description.
+
+    """
+
+
+@expect('D205: 1 blank line required between summary line and description '
+        '(found 2)')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multi_line_two_separating_blanks():
+    """Summary.
+
+
+    Description.
+
+    """
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multi_line_one_separating_blanks():
+    """Summary.
+
+    Description.
+
+    """
+
+
+@expect('D207: Docstring is under-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdf():
+    """Summary.
+
+Description.
+
+    """
+
+
+@expect('D207: Docstring is under-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdsdfsdffsdf():
+    """Summary.
+
+    Description.
+
+"""
+
+
+@expect('D208: Docstring is over-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdsdf24():
+    """Summary.
+
+       Description.
+
+    """
+
+
+@expect('D208: Docstring is over-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdsdfsdf24():
+    """Summary.
+
+    Description.
+
+        """
+
+
+@expect('D208: Docstring is over-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdfsdsdsdfsdf24():
+    """Summary.
+
+        Description.
+
+    """
+
+
+@expect('D209: Multi-line docstring closing quotes should be on a separate '
+        'line')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfljdf24():
+    """Summary.
+
+    Description."""
+
+
+@expect('D210: No whitespaces allowed surrounding docstring text')
+def endswith():
+    """Whitespace at the end. """
+
+
+@expect('D210: No whitespaces allowed surrounding docstring text')
+def around():
+    """ Whitespace at everywhere. """
+
+
+@expect('D210: No whitespaces allowed surrounding docstring text')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multiline():
+    """ Whitespace at the beginning.
+
+    This is the end.
+    """
+
+
+@expect('D300: Use """triple double quotes""" (found \'\'\'-quotes)')
+def triple_single_quotes_raw():
+    r'''Summary.'''
+
+
+@expect('D300: Use """triple double quotes""" (found \'\'\'-quotes)')
+def triple_single_quotes_raw_uppercase():
+    R'''Summary.'''
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+def single_quotes_raw():
+    r'Summary.'
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+def single_quotes_raw_uppercase():
+    R'Summary.'
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+@expect('D301: Use r""" if any backslashes in a docstring')
+def single_quotes_raw_uppercase_backslash():
+    R'Sum\mary.'
+
+
+@expect('D301: Use r""" if any backslashes in a docstring')
+def double_quotes_backslash():
+    """Sum\\mary."""
+
+
+@expect('D301: Use r""" if any backslashes in a docstring')
+def double_quotes_backslash_uppercase():
+    R"""Sum\\mary."""
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def exceptions_of_D301():
+    """Exclude some backslashes from D301.
+
+    In particular, line continuations \
+    and unicode literals \u0394 and \N{GREEK CAPITAL LETTER DELTA}.
+    They are considered to be intentionally unescaped.
+    """
+
+
+@expect("D400: First line should end with a period (not 'y')")
+@expect("D415: First line should end with a period, question mark, "
+        "or exclamation point (not 'y')")
+def lwnlkjl():
+    """Summary"""
+
+
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Return', not 'Returns')")
+def liouiwnlkjl():
+    """Returns foo."""
+
+
+@expect("D401: First line should be in imperative mood; try rephrasing "
+        "(found 'Constructor')")
+def sdgfsdg23245():
+    """Constructor for a foo."""
+
+
+@expect("D401: First line should be in imperative mood; try rephrasing "
+        "(found 'Constructor')")
+def sdgfsdg23245777():
+    """Constructor."""
+
+
+@expect('D402: First line should not be the function\'s "signature"')
+def foobar():
+    """Signature: foobar()."""
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def new_209():
+    """First line.
+
+    More lines.
+    """
+    pass
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def old_209():
+    """One liner.
+
+    Multi-line comments. OK to have extra blank line
+
+    """
+
+
+@expect("D103: Missing docstring in public function")
+def oneliner_d102(): return
+
+
+@expect("D400: First line should end with a period (not 'r')")
+@expect("D415: First line should end with a period, question mark,"
+        " or exclamation point (not 'r')")
+def oneliner_withdoc(): """One liner"""
+
+
+def ignored_decorator(func):   # noqa: D400,D401,D415
+    """Runs something"""
+    func()
+    pass
+
+
+def decorator_for_test(func):   # noqa: D400,D401,D415
+    """Runs something"""
+    func()
+    pass
+
+
+@ignored_decorator
+def oneliner_ignored_decorator(): """One liner"""
+
+
+@decorator_for_test
+@expect("D400: First line should end with a period (not 'r')")
+@expect("D415: First line should end with a period, question mark,"
+        " or exclamation point (not 'r')")
+def oneliner_with_decorator_expecting_errors(): """One liner"""
+
+
+@decorator_for_test
+def valid_oneliner_with_decorator(): """One liner."""
+
+
+@expect("D207: Docstring is under-indented")
+@expect('D213: Multi-line docstring summary should start at the second line')
+def docstring_start_in_same_line(): """First Line.
+
+    Second Line
+    """
+
+
+def function_with_lambda_arg(x=lambda y: y):
+    """Wrap the given lambda."""
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def a_following_valid_function(x=None):
+    """Check for a bug where the previous function caused an assertion.
+
+    The assertion was caused in the next function, so this one is necessary.
+
+    """
+
+
+def outer_function():
+    """Do something."""
+    def inner_function():
+        """Do inner something."""
+        return 0
+
+
+@expect("D400: First line should end with a period (not 'g')")
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Run', not 'Runs')")
+@expect("D415: First line should end with a period, question mark, "
+        "or exclamation point (not 'g')")
+def docstring_bad():
+    """Runs something"""
+    pass
+
+
+def docstring_bad_ignore_all():  # noqa
+    """Runs something"""
+    pass
+
+
+def docstring_bad_ignore_one():  # noqa: D400,D401,D415
+    """Runs something"""
+    pass
+
+
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Run', not 'Runs')")
+def docstring_ignore_some_violations_but_catch_D401():  # noqa: E501,D400,D415
+    """Runs something"""
+    pass
+
+
+@expect(
+    "D401: First line should be in imperative mood "
+    "(perhaps 'Initiate', not 'Initiates')"
+)
+def docstring_initiates():
+    """Initiates the process."""
+
+
+@expect(
+    "D401: First line should be in imperative mood "
+    "(perhaps 'Initialize', not 'Initializes')"
+)
+def docstring_initializes():
+    """Initializes the process."""
+
+
+@wraps(docstring_bad_ignore_one)
+def bad_decorated_function():
+    """Bad (E501) but decorated"""
+    pass
+
+
+def valid_google_string():  # noqa: D400
+    """Test a valid something!"""
+
+
+@expect("D415: First line should end with a period, question mark, "
+        "or exclamation point (not 'g')")
+def bad_google_string():  # noqa: D400
+    """Test a valid something"""
+
+
+# This is reproducing a bug where AttributeError is raised when parsing class
+# parameters as functions for Google / Numpy conventions.
+class Blah:  # noqa: D203,D213
+    """A Blah.
+
+    Parameters
+    ----------
+    x : int
+
+    """
+
+    def __init__(self, x):
+        pass
+
+
+expect(os.path.normcase(__file__ if __file__[-1] != 'c' else __file__[:-1]),
+       'D100: Missing docstring in public module')

resources/test/fixtures/F401_0.py

@@ -61,7 +61,28 @@ Y = TypeVar("Y", bound="Dict")
 Z = TypeVar("Z", "List", "Set")
 
 a = list["Fruit"]
-b = Union["Nut", None]
+b = Union["""Nut""", None]
 c = cast("Vegetable", b)
 
 Field = lambda default=MISSING: field(default=default)
+
+
+# Test: access a sub-importation via an alias.
+import pyarrow as pa
+import pyarrow.csv
+
+print(pa.csv.read_csv("test.csv"))
+
+
+# Test: referencing an import via TypeAlias.
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F401_1.py

@@ -0,0 +1,5 @@
+"""Access a sub-importation via an alias."""
+import pyarrow as pa
+import pyarrow.csv
+
+print(pa.csv.read_csv("test.csv"))

resources/test/fixtures/F401_2.py

@@ -0,0 +1,12 @@
+"""Test: referencing an import via TypeAlias."""
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F401_3.py

@@ -0,0 +1,14 @@
+"""Test: referencing an import via TypeAlias (with future annotations)."""
+from __future__ import annotations
+
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = np.int8 | np.int16

resources/test/fixtures/F401_4.py

@@ -0,0 +1,14 @@
+"""Test: referencing an import via TypeAlias (with future annotations and quotes)."""
+from __future__ import annotations
+
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F404.py

@@ -1,4 +1,3 @@
-from __future__ import print_function
 """Docstring"""
 from __future__ import absolute_import
 

resources/test/fixtures/F821.py

@@ -122,3 +122,12 @@ class PEP593Test:
         dict["foo", "bar"],  # Expected to fail as undefined.
         123,
     ]
+
+
+def in_ipython_notebook() -> bool:
+    try:
+        # autoimported by notebooks
+        get_ipython()  # type: ignore[name-defined]
+    except NameError:
+        return False  # not in notebook
+    return True

resources/test/fixtures/M001.py

@@ -15,6 +15,9 @@ def f() -> None:
     # Invalid
     d = 1  # noqa: F841, E501
 
+    # Invalid (and unimplemented)
+    d = 1  # noqa: F841, W191
+
 
 # Valid
 _ = """Lorem ipsum dolor sit amet.

resources/test/fixtures/N801.py

@@ -0,0 +1,34 @@
+class bad:
+    pass
+
+
+class _bad:
+    pass
+
+
+class bad_class:
+    pass
+
+
+class Bad_Class:
+    pass
+
+
+class BAD_CLASS:
+    pass
+
+
+class Good:
+    pass
+
+
+class _Good:
+    pass
+
+
+class GoodClass:
+    pass
+
+
+class GOOD:
+    pass

resources/test/fixtures/N802.py

@@ -0,0 +1,26 @@
+def Bad():
+    pass
+
+
+def _Bad():
+    pass
+
+
+def BAD():
+    pass
+
+
+def BAD_FUNC():
+    pass
+
+
+def good():
+    pass
+
+
+def _good():
+    pass
+
+
+def good_func():
+    pass

resources/test/fixtures/N803.py

@@ -0,0 +1,7 @@
+def func(a, A):
+    return a, A
+
+
+class Class:
+    def method(self, a, A):
+        return a, A

resources/test/fixtures/N804.py

@@ -0,0 +1,19 @@
+class Class:
+    @classmethod
+    def bad_class_method(this):
+        pass
+
+    @classmethod
+    def good_class_method(cls):
+        pass
+
+    def method(self):
+        pass
+
+    @staticmethod
+    def static_method(x):
+        return x
+
+
+def func(x):
+    return x

resources/test/fixtures/N805.py

@@ -0,0 +1,26 @@
+import random
+
+
+class Class:
+    def bad_method(this):
+        pass
+
+    if random.random(0, 2) == 0:
+
+        def extra_bad_method(this):
+            pass
+
+    def good_method(self):
+        pass
+
+    @classmethod
+    def class_method(cls):
+        pass
+
+    @staticmethod
+    def static_method(x):
+        return x
+
+
+def func(x):
+    return x

resources/test/fixtures/U005.py

@@ -1,3 +1,10 @@
-self.assertEquals (1, 2)
-self.assertEquals(1, 2)
-self.assertEqual(3, 4)
+import unittest
+
+
+class Suite(unittest.TestCase):
+    def test(self) -> None:
+        self.assertEquals (1, 2)
+        self.assertEquals(1, 2)
+        self.assertEqual(3, 4)
+        self.failUnlessAlmostEqual(1, 1.1)
+        self.assertNotRegexpMatches("a", "b")

resources/test/fixtures/U006.py

@@ -0,0 +1,12 @@
+from typing import List
+
+
+def f(x: List[str]) -> None:
+    ...
+
+
+import typing
+
+
+def f(x: typing.List[str]) -> None:
+    ...

resources/test/fixtures/U007.py

@@ -0,0 +1,40 @@
+from typing import Optional
+
+
+def f(x: Optional[str]) -> None:
+    ...
+
+
+import typing
+
+
+def f(x: typing.Optional[str]) -> None:
+    ...
+
+
+from typing import Union
+
+
+def f(x: Union[str, int, Union[float, bytes]]) -> None:
+    ...
+
+
+import typing
+
+
+def f(x: typing.Union[str, int]) -> None:
+    ...
+
+
+from typing import Union
+
+
+def f(x: "Union[str, int, Union[float, bytes]]") -> None:
+    ...
+
+
+import typing
+
+
+def f(x: "typing.Union[str, int]") -> None:
+    ...

resources/test/fixtures/W292_0.py

@@ -0,0 +1,2 @@
+def fn() -> None:
+    pass

resources/test/fixtures/W292_1.py

@@ -0,0 +1,2 @@
+def fn() -> None:
+    pass  # noqa: W292

resources/test/fixtures/W292_2.py

@@ -0,0 +1,2 @@
+def fn() -> None:
+    pass

resources/test/fixtures/canonical_google_examples.py

@@ -0,0 +1,108 @@
+"""A one line summary of the module or program, terminated by a period.
+
+Leave one blank line.  The rest of this docstring should contain an
+overall description of the module or program.  Optionally, it may also
+contain a brief description of exported classes and functions and/or usage
+examples.
+
+  Typical usage example:
+
+  foo = ClassFoo()
+  bar = foo.FunctionBar()
+"""
+# above: "2.8.2 Modules" section example
+# https://google.github.io/styleguide/pyguide.html#382-modules
+
+# Examples from the official "Google Python Style Guide" documentation:
+#     * As HTML: https://google.github.io/styleguide/pyguide.html
+#     * Source Markdown:
+#         https://github.com/google/styleguide/blob/gh-pages/pyguide.md
+
+import os
+from .expected import Expectation
+
+expectation = Expectation()
+expect = expectation.expect
+
+# module docstring expected violations:
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D213: Multi-line docstring summary should start at the second line"))
+
+
+# "3.8.3 Functions and Methods" section example
+# https://google.github.io/styleguide/pyguide.html#383-functions-and-methods
+@expect("D213: Multi-line docstring summary should start at the second line",
+        arg_count=3)
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Fetch', not 'Fetches')", arg_count=3)
+@expect("D406: Section name should end with a newline "
+        "('Raises', not 'Raises:')", arg_count=3)
+@expect("D406: Section name should end with a newline "
+        "('Returns', not 'Returns:')", arg_count=3)
+@expect("D407: Missing dashed underline after section ('Raises')", arg_count=3)
+@expect("D407: Missing dashed underline after section ('Returns')",
+        arg_count=3)
+@expect("D413: Missing blank line after last section ('Raises')", arg_count=3)
+def fetch_bigtable_rows(big_table, keys, other_silly_variable=None):
+    """Fetches rows from a Bigtable.
+
+    Retrieves rows pertaining to the given keys from the Table instance
+    represented by big_table.  Silly things may happen if
+    other_silly_variable is not None.
+
+    Args:
+        big_table: An open Bigtable Table instance.
+        keys: A sequence of strings representing the key of each table row
+            to fetch.
+        other_silly_variable: Another optional variable, that has a much
+            longer name than the other args, and which does nothing.
+
+    Returns:
+        A dict mapping keys to the corresponding table row data
+        fetched. Each row is represented as a tuple of strings. For
+        example:
+
+        {'Serak': ('Rigel VII', 'Preparer'),
+         'Zim': ('Irk', 'Invader'),
+         'Lrrr': ('Omicron Persei 8', 'Emperor')}
+
+        If a key from the keys argument is missing from the dictionary,
+        then that row was not found in the table.
+
+    Raises:
+        IOError: An error occurred accessing the bigtable.Table object.
+    """
+
+
+# "3.8.4 Classes" section example
+# https://google.github.io/styleguide/pyguide.html#384-classes
+@expect("D203: 1 blank line required before class docstring (found 0)")
+@expect("D213: Multi-line docstring summary should start at the second line")
+@expect("D406: Section name should end with a newline "
+        "('Attributes', not 'Attributes:')")
+@expect("D407: Missing dashed underline after section ('Attributes')")
+@expect("D413: Missing blank line after last section ('Attributes')")
+class SampleClass:
+    """Summary of class here.
+
+    Longer class information....
+    Longer class information....
+
+    Attributes:
+        likes_spam: A boolean indicating if we like SPAM or not.
+        eggs: An integer count of the eggs we have laid.
+    """
+
+    @expect("D401: First line should be in imperative mood "
+            "(perhaps 'Init', not 'Inits')", arg_count=2)
+    def __init__(self, likes_spam=False):
+        """Inits SampleClass with blah."""
+        if self:  # added to avoid NameError when run via @expect decorator
+            self.likes_spam = likes_spam
+            self.eggs = 0
+
+    @expect("D401: First line should be in imperative mood "
+            "(perhaps 'Perform', not 'Performs')", arg_count=1)
+    def public_method(self):
+        """Performs operation blah."""

resources/test/fixtures/canonical_numpy_examples.py

@@ -0,0 +1,163 @@
+"""This is the docstring for the example.py module.  Modules names should
+have short, all-lowercase names.  The module name may have underscores if
+this improves readability.
+
+Every module should have a docstring at the very top of the file.  The
+module's docstring may extend over multiple lines.  If your docstring does
+extend over multiple lines, the closing three quotation marks must be on
+a line by itself, preferably preceded by a blank line.
+
+"""
+
+# Example source file from the official "numpydoc docstring guide"
+# documentation (with the modification of commenting out all the original
+# ``import`` lines, plus adding this note and ``Expectation`` code):
+#     * As HTML: https://numpydoc.readthedocs.io/en/latest/example.html
+#     * Source Python:
+#         https://github.com/numpy/numpydoc/blob/master/doc/example.py
+
+# from __future__ import division, absolute_import, print_function
+#
+# import os  # standard library imports first
+#
+# Do NOT import using *, e.g. from numpy import *
+#
+# Import the module using
+#
+#   import numpy
+#
+# instead or import individual functions as needed, e.g
+#
+#  from numpy import array, zeros
+#
+# If you prefer the use of abbreviated module names, we suggest the
+# convention used by NumPy itself::
+#
+# import numpy as np
+# import matplotlib as mpl
+# import matplotlib.pyplot as plt
+#
+# These abbreviated names are not to be used in docstrings; users must
+# be able to paste and execute docstrings after importing only the
+# numpy module itself, unabbreviated.
+
+import os
+from .expected import Expectation
+
+expectation = Expectation()
+expect = expectation.expect
+
+# module docstring expected violations:
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D205: 1 blank line required between summary line and description "
+    "(found 0)"))
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D213: Multi-line docstring summary should start at the second line"))
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D400: First line should end with a period (not 'd')"))
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D404: First word of the docstring should not be `This`"))
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D415: First line should end with a period, question mark, or exclamation "
+    "point (not 'd')"))
+
+
+@expect("D213: Multi-line docstring summary should start at the second line",
+        arg_count=3)
+@expect("D401: First line should be in imperative mood; try rephrasing "
+        "(found 'A')", arg_count=3)
+@expect("D413: Missing blank line after last section ('Examples')",
+        arg_count=3)
+def foo(var1, var2, long_var_name='hi'):
+    r"""A one-line summary that does not use variable names.
+
+    Several sentences providing an extended description. Refer to
+    variables using back-ticks, e.g. `var`.
+
+    Parameters
+    ----------
+    var1 : array_like
+        Array_like means all those objects -- lists, nested lists, etc. --
+        that can be converted to an array.  We can also refer to
+        variables like `var1`.
+    var2 : int
+        The type above can either refer to an actual Python type
+        (e.g. ``int``), or describe the type of the variable in more
+        detail, e.g. ``(N,) ndarray`` or ``array_like``.
+    long_var_name : {'hi', 'ho'}, optional
+        Choices in brackets, default first when optional.
+
+    Returns
+    -------
+    type
+        Explanation of anonymous return value of type ``type``.
+    describe : type
+        Explanation of return value named `describe`.
+    out : type
+        Explanation of `out`.
+    type_without_description
+
+    Other Parameters
+    ----------------
+    only_seldom_used_keywords : type
+        Explanation
+    common_parameters_listed_above : type
+        Explanation
+
+    Raises
+    ------
+    BadException
+        Because you shouldn't have done that.
+
+    See Also
+    --------
+    numpy.array : Relationship (optional).
+    numpy.ndarray : Relationship (optional), which could be fairly long, in
+                    which case the line wraps here.
+    numpy.dot, numpy.linalg.norm, numpy.eye
+
+    Notes
+    -----
+    Notes about the implementation algorithm (if needed).
+
+    This can have multiple paragraphs.
+
+    You may include some math:
+
+    .. math:: X(e^{j\omega } ) = x(n)e^{ - j\omega n}
+
+    And even use a Greek symbol like :math:`\omega` inline.
+
+    References
+    ----------
+    Cite the relevant literature, e.g. [1]_.  You may also cite these
+    references in the notes section above.
+
+    .. [1] O. McNoleg, "The integration of GIS, remote sensing,
+       expert systems and adaptive co-kriging for environmental habitat
+       modelling of the Highland Haggis using object-oriented, fuzzy-logic
+       and neural-network techniques," Computers & Geosciences, vol. 22,
+       pp. 585-588, 1996.
+
+    Examples
+    --------
+    These are written in doctest format, and should illustrate how to
+    use the function.
+
+    >>> a = [1, 2, 3]
+    >>> print([x + 3 for x in a])
+    [4, 5, 6]
+    >>> print("a\nb")
+    a
+    b
+    """
+    # After closing class docstring, there should be one blank line to
+    # separate following codes (according to PEP257).
+    # But for function, method and module, there should be no blank lines
+    # after closing the docstring.
+    pass

resources/test/fixtures/sections.py

@@ -0,0 +1,497 @@
+"""A valid module docstring."""
+
+from .expected import Expectation
+
+expectation = Expectation()
+expect = expectation.expect
+
+
+_D213 = 'D213: Multi-line docstring summary should start at the second line'
+_D400 = "D400: First line should end with a period (not '!')"
+
+
+@expect(_D213)
+@expect("D405: Section name should be properly capitalized "
+        "('Returns', not 'returns')")
+def not_capitalized():  # noqa: D416
+    """Toggle the gizmo.
+
+    returns
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D406: Section name should end with a newline "
+        "('Returns', not 'Returns:')")
+def superfluous_suffix():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns:
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D407: Missing dashed underline after section ('Returns')")
+def no_underline():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D407: Missing dashed underline after section ('Returns')")
+@expect("D414: Section has no content ('Returns')")
+def no_underline_and_no_description():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+
+    """
+
+
+@expect(_D213)
+@expect("D410: Missing blank line after section ('Returns')")
+@expect("D414: Section has no content ('Returns')")
+@expect("D411: Missing blank line before section ('Yields')")
+@expect("D414: Section has no content ('Yields')")
+def consecutive_sections():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+    -------
+    Yields
+    ------
+
+    Raises
+    ------
+    Questions.
+
+    """
+
+
+@expect(_D213)
+@expect("D408: Section underline should be in the line following the "
+        "section's name ('Returns')")
+def blank_line_before_underline():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D409: Section underline should match the length of its name "
+        "(Expected 7 dashes in section 'Returns', got 2)")
+def bad_underline_length():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+    --
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D413: Missing blank line after last section ('Returns')")
+def no_blank_line_after_last_section():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+    -------
+    A value of some sort.
+    """
+
+
+@expect(_D213)
+@expect("D411: Missing blank line before section ('Returns')")
+def no_blank_line_before_section():  # noqa: D416
+    """Toggle the gizmo.
+
+    The function's description.
+    Returns
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D214: Section is over-indented ('Returns')")
+def section_overindented():  # noqa: D416
+    """Toggle the gizmo.
+
+        Returns
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D215: Section underline is over-indented (in section 'Returns')")
+def section_underline_overindented():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+        -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D215: Section underline is over-indented (in section 'Returns')")
+@expect("D413: Missing blank line after last section ('Returns')")
+@expect("D414: Section has no content ('Returns')")
+def section_underline_overindented_and_contentless():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+        -------
+    """
+
+
+@expect(_D213)
+def ignore_non_actual_section():  # noqa: D416
+    """Toggle the gizmo.
+
+    This is the function's description, which will also specify what it
+    returns
+
+    """
+
+
+@expect(_D213)
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Return', not 'Returns')")
+@expect("D400: First line should end with a period (not 's')")
+@expect("D415: First line should end with a period, question "
+        "mark, or exclamation point (not 's')")
+@expect("D205: 1 blank line required between summary line and description "
+        "(found 0)")
+def section_name_in_first_line():  # noqa: D416
+    """Returns
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D405: Section name should be properly capitalized "
+        "('Short Summary', not 'Short summary')")
+@expect("D412: No blank lines allowed between a section header and its "
+        "content ('Short Summary')")
+@expect("D409: Section underline should match the length of its name "
+        "(Expected 7 dashes in section 'Returns', got 6)")
+@expect("D410: Missing blank line after section ('Returns')")
+@expect("D411: Missing blank line before section ('Raises')")
+@expect("D406: Section name should end with a newline "
+        "('Raises', not 'Raises:')")
+@expect("D407: Missing dashed underline after section ('Raises')")
+def multiple_sections():  # noqa: D416
+    """Toggle the gizmo.
+
+    Short summary
+    -------------
+
+    This is the function's description, which will also specify what it
+    returns.
+
+    Returns
+    ------
+    Many many wonderful things.
+    Raises:
+    My attention.
+
+    """
+
+
+@expect(_D213)
+def false_positive_section_prefix():  # noqa: D416
+    """Toggle the gizmo.
+
+    Parameters
+    ----------
+    attributes_are_fun: attributes for the function.
+
+    """
+
+
+@expect(_D213)
+def section_names_as_parameter_names():  # noqa: D416
+    """Toggle the gizmo.
+
+    Parameters
+    ----------
+    notes : list
+        A list of wonderful notes.
+    examples: list
+        A list of horrible examples.
+
+    """
+
+
+@expect(_D213)
+@expect("D414: Section has no content ('Returns')")
+def valid_google_style_section():  # noqa: D406, D407
+    """Toggle the gizmo.
+
+    Args:
+        note: A random string.
+
+    Returns:
+
+    Raises:
+        RandomError: A random error that occurs randomly.
+
+    """
+
+
+@expect(_D213)
+@expect("D416: Section name should end with a colon "
+        "('Args:', not 'Args')")
+def missing_colon_google_style_section():  # noqa: D406, D407
+    """Toggle the gizmo.
+
+    Args
+        note: A random string.
+
+    """
+
+
+@expect("D417: Missing argument descriptions in the docstring "
+        "(argument(s) y are missing descriptions in "
+        "'bar' docstring)", func_name="bar")
+def _test_nested_functions():
+    x = 1
+
+    def bar(y=2):  # noqa: D207, D213, D406, D407
+        """Nested function test for docstrings.
+
+        Will this work when referencing x?
+
+        Args:
+            x: Test something
+that is broken.
+
+        """
+        print(x)
+
+
+@expect(_D213)
+@expect("D417: Missing argument descriptions in the docstring "
+        "(argument(s) y are missing descriptions in "
+        "'test_missing_google_args' docstring)")
+def test_missing_google_args(x=1, y=2, _private=3):  # noqa: D406, D407
+    """Toggle the gizmo.
+
+    Args:
+        x (int): The greatest integer.
+
+    """
+
+
+class TestGoogle:  # noqa: D203
+    """Test class."""
+
+    def test_method(self, test, another_test, _):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            test: A parameter.
+            another_test: Another parameter.
+
+        """
+
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) test, y, z are missing descriptions in "
+            "'test_missing_args' docstring)", arg_count=5)
+    def test_missing_args(self, test, x, y, z=3, _private_arg=3):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            x: Another parameter.
+
+        """
+
+    @classmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) test, y, z are missing descriptions in "
+            "'test_missing_args_class_method' docstring)", arg_count=5)
+    def test_missing_args_class_method(cls, test, x, y, _, z=3):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            x: Another parameter. The parameter below is missing description.
+            y:
+
+        """
+
+    @staticmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) a, y, z are missing descriptions in "
+            "'test_missing_args_static_method' docstring)", arg_count=4)
+    def test_missing_args_static_method(a, x, y, _test, z=3):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            x: Another parameter.
+
+        """
+
+    @staticmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) a, b are missing descriptions in "
+            "'test_missing_docstring' docstring)", arg_count=2)
+    def test_missing_docstring(a, b):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            a:
+
+        """
+
+    @staticmethod
+    def test_hanging_indent(skip, verbose):  # noqa: D213, D407
+        """Do stuff.
+
+        Args:
+            skip (:attr:`.Skip`):
+                Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+                Etiam at tellus a tellus faucibus maximus. Curabitur tellus
+                mauris, semper id vehicula ac, feugiat ut tortor.
+            verbose (bool):
+                If True, print out as much infromation as possible.
+                If False, print out concise "one-liner" information.
+
+        """
+
+
+@expect(_D213)
+@expect("D417: Missing argument descriptions in the docstring "
+        "(argument(s) y are missing descriptions in "
+        "'test_missing_numpy_args' docstring)")
+def test_missing_numpy_args(_private_arg=0, x=1, y=2):  # noqa: D406, D407
+    """Toggle the gizmo.
+
+    Parameters
+    ----------
+    x : int
+        The greatest integer in the history \
+of the entire world.
+
+    """
+
+
+class TestNumpy:  # noqa: D203
+    """Test class."""
+
+    def test_method(self, test, another_test, z, _, x=1, y=2, _private_arg=1):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Some long string with a \
+line continuation.
+
+        Parameters
+        ----------
+        test, another_test
+            Some parameters without type.
+        z : some parameter with a very long type description that requires a \
+line continuation.
+            But no further description.
+        x, y : int
+            Some integer parameters.
+
+        """
+
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) test, y, z are missing descriptions in "
+            "'test_missing_args' docstring)", arg_count=5)
+    def test_missing_args(self, test, x, y, z=3, t=1, _private=0):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Parameters
+        ----------
+        x, t : int
+            Some parameters.
+
+
+        """
+
+    @classmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) test, y, z are missing descriptions in "
+            "'test_missing_args_class_method' docstring)", arg_count=4)
+    def test_missing_args_class_method(cls, test, x, y, z=3):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Parameters
+        ----------
+        z
+        x
+            Another parameter. The parameters y, test below are
+            missing descriptions. The parameter z above is also missing
+            a description.
+        y
+        test
+
+        """
+
+    @staticmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) a, z are missing descriptions in "
+            "'test_missing_args_static_method' docstring)", arg_count=3)
+    def test_missing_args_static_method(a, x, y, z=3, t=1):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Parameters
+        ----------
+        x, y
+            Another parameter.
+        t : int
+            Yet another parameter.
+
+        """
+
+    @staticmethod
+    def test_mixing_numpy_and_google(danger):  # noqa: D213
+        """Repro for #388.
+
+        Parameters
+        ----------
+        danger
+            Zoneeeeee!
+
+        """
+
+
+class TestIncorrectIndent:  # noqa: D203
+    """Test class."""
+
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) y are missing descriptions in "
+            "'test_incorrect_indent' docstring)", arg_count=3)
+    def test_incorrect_indent(self, x=1, y=2):  # noqa: D207, D213, D407
+        """Reproducing issue #437.
+
+Testing this incorrectly indented docstring.
+
+        Args:
+            x: Test argument.
+
+        """

scripts/.flake8

@@ -0,0 +1,19 @@
+[flake8]
+exclude =
+    # Defaults
+    .svn,
+    CVS,
+    .bzr,
+    .hg,
+    .git,
+    __pycache__,
+    .tox,
+    .idea,
+    .mypy_cache,
+    .venv,
+    node_modules,
+    # Custom
+    _state_machine.py,
+    test_fstring.py,
+    bad_coding2.py,
+    badsyntax_*.py

setup.py

@@ -0,0 +1,23 @@
+import sys
+
+from setuptools import setup
+
+sys.stderr.write(
+    """
+===============================
+Unsupported installation method
+===============================
+ruff no longer supports installation with `python setup.py install`.
+Please use `python -m pip install .` instead.
+"""
+)
+sys.exit(1)
+
+
+# The below code will never execute, however GitHub is particularly
+# picky about where it finds Python packaging metadata.
+# See: https://github.com/github/feedback/discussions/6456
+#
+# To be removed once GitHub catches up.
+
+setup(name="ruff", install_requires=[])

src/ast.rs

@@ -1,4 +1,4 @@
-pub mod checks;
+pub mod helpers;
 pub mod operations;
 pub mod relocate;
 pub mod types;

src/ast/checks.rs

@@ -1,955 +0,0 @@
-use std::collections::BTreeSet;
-
-use itertools::izip;
-use regex::Regex;
-use rustpython_parser::ast::{
-    Arg, ArgData, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind,
-    Stmt, StmtKind, Unaryop,
-};
-use serde::{Deserialize, Serialize};
-
-use crate::ast::types::{
-    Binding, BindingKind, CheckLocator, FunctionScope, Range, Scope, ScopeKind,
-};
-use crate::checks::{Check, CheckKind, RejectedCmpop};
-use crate::python::builtins::BUILTINS;
-
-/// Check IfTuple compliance.
-pub fn check_if_tuple(test: &Expr, location: Range) -> Option<Check> {
-    if let ExprKind::Tuple { elts, .. } = &test.node {
-        if !elts.is_empty() {
-            return Some(Check::new(CheckKind::IfTuple, location));
-        }
-    }
-    None
-}
-
-/// Check AssertTuple compliance.
-pub fn check_assert_tuple(test: &Expr, location: Range) -> Option<Check> {
-    if let ExprKind::Tuple { elts, .. } = &test.node {
-        if !elts.is_empty() {
-            return Some(Check::new(CheckKind::AssertTuple, location));
-        }
-    }
-    None
-}
-
-/// Check NotInTest and NotIsTest compliance.
-pub fn check_not_tests(
-    op: &Unaryop,
-    operand: &Expr,
-    check_not_in: bool,
-    check_not_is: bool,
-    locator: &dyn CheckLocator,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    if matches!(op, Unaryop::Not) {
-        if let ExprKind::Compare { ops, .. } = &operand.node {
-            for op in ops {
-                match op {
-                    Cmpop::In => {
-                        if check_not_in {
-                            checks.push(Check::new(
-                                CheckKind::NotInTest,
-                                locator.locate_check(Range::from_located(operand)),
-                            ));
-                        }
-                    }
-                    Cmpop::Is => {
-                        if check_not_is {
-                            checks.push(Check::new(
-                                CheckKind::NotIsTest,
-                                locator.locate_check(Range::from_located(operand)),
-                            ));
-                        }
-                    }
-                    _ => {}
-                }
-            }
-        }
-    }
-
-    checks
-}
-
-/// Check UnusedVariable compliance.
-pub fn check_unused_variables(
-    scope: &Scope,
-    locator: &dyn CheckLocator,
-    dummy_variable_rgx: &Regex,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    if matches!(
-        scope.kind,
-        ScopeKind::Function(FunctionScope { uses_locals: true })
-    ) {
-        return checks;
-    }
-
-    for (name, binding) in scope.values.iter() {
-        if binding.used.is_none()
-            && matches!(binding.kind, BindingKind::Assignment)
-            && !dummy_variable_rgx.is_match(name)
-            && name != "__tracebackhide__"
-            && name != "__traceback_info__"
-            && name != "__traceback_supplement__"
-        {
-            checks.push(Check::new(
-                CheckKind::UnusedVariable(name.to_string()),
-                locator.locate_check(binding.range),
-            ));
-        }
-    }
-
-    checks
-}
-
-/// Check DoNotAssignLambda compliance.
-pub fn check_do_not_assign_lambda(value: &Expr, location: Range) -> Option<Check> {
-    if let ExprKind::Lambda { .. } = &value.node {
-        Some(Check::new(CheckKind::DoNotAssignLambda, location))
-    } else {
-        None
-    }
-}
-
-/// Check UselessMetaclassType compliance.
-pub fn check_useless_metaclass_type(
-    targets: &Vec<Expr>,
-    value: &Expr,
-    location: Range,
-) -> Option<Check> {
-    if targets.len() == 1 {
-        if let ExprKind::Name { id, .. } = targets.first().map(|expr| &expr.node).unwrap() {
-            if id == "__metaclass__" {
-                if let ExprKind::Name { id, .. } = &value.node {
-                    if id == "type" {
-                        return Some(Check::new(CheckKind::UselessMetaclassType, location));
-                    }
-                }
-            }
-        }
-    }
-    None
-}
-
-/// Check UnnecessaryAbspath compliance.
-pub fn check_unnecessary_abspath(func: &Expr, args: &Vec<Expr>, location: Range) -> Option<Check> {
-    // Validate the arguments.
-    if args.len() == 1 {
-        if let ExprKind::Name { id, .. } = &args[0].node {
-            if id == "__file__" {
-                match &func.node {
-                    ExprKind::Attribute { attr: id, .. } | ExprKind::Name { id, .. } => {
-                        if id == "abspath" {
-                            return Some(Check::new(CheckKind::UnnecessaryAbspath, location));
-                        }
-                    }
-                    _ => {}
-                }
-            }
-        }
-    }
-
-    None
-}
-
-#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
-pub enum Primitive {
-    Bool,
-    Str,
-    Bytes,
-    Int,
-    Float,
-    Complex,
-}
-
-impl Primitive {
-    fn from_constant(constant: &Constant) -> Option<Self> {
-        match constant {
-            Constant::Bool(_) => Some(Primitive::Bool),
-            Constant::Str(_) => Some(Primitive::Str),
-            Constant::Bytes(_) => Some(Primitive::Bytes),
-            Constant::Int(_) => Some(Primitive::Int),
-            Constant::Float(_) => Some(Primitive::Float),
-            Constant::Complex { .. } => Some(Primitive::Complex),
-            _ => None,
-        }
-    }
-
-    pub fn builtin(&self) -> String {
-        match self {
-            Primitive::Bool => "bool".to_string(),
-            Primitive::Str => "str".to_string(),
-            Primitive::Bytes => "bytes".to_string(),
-            Primitive::Int => "int".to_string(),
-            Primitive::Float => "float".to_string(),
-            Primitive::Complex => "complex".to_string(),
-        }
-    }
-}
-
-/// Check TypeOfPrimitive compliance.
-pub fn check_type_of_primitive(func: &Expr, args: &Vec<Expr>, location: Range) -> Option<Check> {
-    // Validate the arguments.
-    if args.len() == 1 {
-        match &func.node {
-            ExprKind::Attribute { attr: id, .. } | ExprKind::Name { id, .. } => {
-                if id == "type" {
-                    if let ExprKind::Constant { value, .. } = &args[0].node {
-                        if let Some(primitive) = Primitive::from_constant(value) {
-                            return Some(Check::new(
-                                CheckKind::TypeOfPrimitive(primitive),
-                                location,
-                            ));
-                        }
-                    }
-                }
-            }
-            _ => {}
-        }
-    }
-
-    None
-}
-
-fn is_ambiguous_name(name: &str) -> bool {
-    name == "l" || name == "I" || name == "O"
-}
-
-/// Check AmbiguousVariableName compliance.
-pub fn check_ambiguous_variable_name(name: &str, location: Range) -> Option<Check> {
-    if is_ambiguous_name(name) {
-        Some(Check::new(
-            CheckKind::AmbiguousVariableName(name.to_string()),
-            location,
-        ))
-    } else {
-        None
-    }
-}
-
-/// Check AmbiguousClassName compliance.
-pub fn check_ambiguous_class_name(name: &str, location: Range) -> Option<Check> {
-    if is_ambiguous_name(name) {
-        Some(Check::new(
-            CheckKind::AmbiguousClassName(name.to_string()),
-            location,
-        ))
-    } else {
-        None
-    }
-}
-
-/// Check AmbiguousFunctionName compliance.
-pub fn check_ambiguous_function_name(name: &str, location: Range) -> Option<Check> {
-    if is_ambiguous_name(name) {
-        Some(Check::new(
-            CheckKind::AmbiguousFunctionName(name.to_string()),
-            location,
-        ))
-    } else {
-        None
-    }
-}
-
-/// Check UselessObjectInheritance compliance.
-pub fn check_useless_object_inheritance(
-    name: &str,
-    bases: &[Expr],
-    scope: &Scope,
-) -> Option<Check> {
-    for expr in bases {
-        if let ExprKind::Name { id, .. } = &expr.node {
-            if id == "object" {
-                match scope.values.get(id) {
-                    None
-                    | Some(Binding {
-                        kind: BindingKind::Builtin,
-                        ..
-                    }) => {
-                        return Some(Check::new(
-                            CheckKind::UselessObjectInheritance(name.to_string()),
-                            Range::from_located(expr),
-                        ));
-                    }
-                    _ => {}
-                }
-            }
-        }
-    }
-
-    None
-}
-
-/// Check DefaultExceptNotLast compliance.
-pub fn check_default_except_not_last(handlers: &Vec<Excepthandler>) -> Option<Check> {
-    for (idx, handler) in handlers.iter().enumerate() {
-        let ExcepthandlerKind::ExceptHandler { type_, .. } = &handler.node;
-        if type_.is_none() && idx < handlers.len() - 1 {
-            return Some(Check::new(
-                CheckKind::DefaultExceptNotLast,
-                Range::from_located(handler),
-            ));
-        }
-    }
-
-    None
-}
-
-/// Check RaiseNotImplemented compliance.
-pub fn check_raise_not_implemented(expr: &Expr) -> Option<Check> {
-    match &expr.node {
-        ExprKind::Call { func, .. } => {
-            if let ExprKind::Name { id, .. } = &func.node {
-                if id == "NotImplemented" {
-                    return Some(Check::new(
-                        CheckKind::RaiseNotImplemented,
-                        Range::from_located(expr),
-                    ));
-                }
-            }
-        }
-        ExprKind::Name { id, .. } => {
-            if id == "NotImplemented" {
-                return Some(Check::new(
-                    CheckKind::RaiseNotImplemented,
-                    Range::from_located(expr),
-                ));
-            }
-        }
-        _ => {}
-    }
-
-    None
-}
-
-/// Check DuplicateArgumentName compliance.
-pub fn check_duplicate_arguments(arguments: &Arguments) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    // Collect all the arguments into a single vector.
-    let mut all_arguments: Vec<&Arg> = arguments
-        .args
-        .iter()
-        .chain(arguments.posonlyargs.iter())
-        .chain(arguments.kwonlyargs.iter())
-        .collect();
-    if let Some(arg) = &arguments.vararg {
-        all_arguments.push(arg);
-    }
-    if let Some(arg) = &arguments.kwarg {
-        all_arguments.push(arg);
-    }
-
-    // Search for duplicates.
-    let mut idents: BTreeSet<&str> = BTreeSet::new();
-    for arg in all_arguments {
-        let ident = &arg.node.arg;
-        if idents.contains(ident.as_str()) {
-            checks.push(Check::new(
-                CheckKind::DuplicateArgumentName,
-                Range::from_located(arg),
-            ));
-        }
-        idents.insert(ident);
-    }
-
-    checks
-}
-
-/// Check AssertEquals compliance.
-pub fn check_assert_equals(expr: &Expr) -> Option<Check> {
-    if let ExprKind::Attribute { value, attr, .. } = &expr.node {
-        if attr == "assertEquals" {
-            if let ExprKind::Name { id, .. } = &value.node {
-                if id == "self" {
-                    return Some(Check::new(
-                        CheckKind::NoAssertEquals,
-                        Range::from_located(expr),
-                    ));
-                }
-            }
-        }
-    }
-    None
-}
-
-#[derive(Debug, PartialEq)]
-enum DictionaryKey<'a> {
-    Constant(&'a Constant),
-    Variable(&'a String),
-}
-
-fn convert_to_value(expr: &Expr) -> Option<DictionaryKey> {
-    match &expr.node {
-        ExprKind::Constant { value, .. } => Some(DictionaryKey::Constant(value)),
-        ExprKind::Name { id, .. } => Some(DictionaryKey::Variable(id)),
-        _ => None,
-    }
-}
-
-/// Check MultiValueRepeatedKeyLiteral and MultiValueRepeatedKeyVariable compliance.
-pub fn check_repeated_keys(
-    keys: &Vec<Expr>,
-    check_repeated_literals: bool,
-    check_repeated_variables: bool,
-    locator: &dyn CheckLocator,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    let num_keys = keys.len();
-    for i in 0..num_keys {
-        let k1 = &keys[i];
-        let v1 = convert_to_value(k1);
-        for k2 in keys.iter().take(num_keys).skip(i + 1) {
-            let v2 = convert_to_value(k2);
-            match (&v1, &v2) {
-                (Some(DictionaryKey::Constant(v1)), Some(DictionaryKey::Constant(v2))) => {
-                    if check_repeated_literals && v1 == v2 {
-                        checks.push(Check::new(
-                            CheckKind::MultiValueRepeatedKeyLiteral,
-                            locator.locate_check(Range::from_located(k2)),
-                        ))
-                    }
-                }
-                (Some(DictionaryKey::Variable(v1)), Some(DictionaryKey::Variable(v2))) => {
-                    if check_repeated_variables && v1 == v2 {
-                        checks.push(Check::new(
-                            CheckKind::MultiValueRepeatedKeyVariable((*v2).to_string()),
-                            locator.locate_check(Range::from_located(k2)),
-                        ))
-                    }
-                }
-                _ => {}
-            }
-        }
-    }
-
-    checks
-}
-
-/// Check TrueFalseComparison and NoneComparison compliance.
-pub fn check_literal_comparisons(
-    left: &Expr,
-    ops: &Vec<Cmpop>,
-    comparators: &Vec<Expr>,
-    check_none_comparisons: bool,
-    check_true_false_comparisons: bool,
-    locator: &dyn CheckLocator,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    let op = ops.first().unwrap();
-    let comparator = left;
-
-    // Check `left`.
-    if check_none_comparisons
-        && matches!(
-            comparator.node,
-            ExprKind::Constant {
-                value: Constant::None,
-                kind: None
-            }
-        )
-    {
-        if matches!(op, Cmpop::Eq) {
-            checks.push(Check::new(
-                CheckKind::NoneComparison(RejectedCmpop::Eq),
-                locator.locate_check(Range::from_located(comparator)),
-            ));
-        }
-        if matches!(op, Cmpop::NotEq) {
-            checks.push(Check::new(
-                CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                locator.locate_check(Range::from_located(comparator)),
-            ));
-        }
-    }
-
-    if check_true_false_comparisons {
-        if let ExprKind::Constant {
-            value: Constant::Bool(value),
-            kind: None,
-        } = comparator.node
-        {
-            if matches!(op, Cmpop::Eq) {
-                checks.push(Check::new(
-                    CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                    locator.locate_check(Range::from_located(comparator)),
-                ));
-            }
-            if matches!(op, Cmpop::NotEq) {
-                checks.push(Check::new(
-                    CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
-                    locator.locate_check(Range::from_located(comparator)),
-                ));
-            }
-        }
-    }
-
-    // Check each comparator in order.
-    for (op, comparator) in izip!(ops, comparators) {
-        if check_none_comparisons
-            && matches!(
-                comparator.node,
-                ExprKind::Constant {
-                    value: Constant::None,
-                    kind: None
-                }
-            )
-        {
-            if matches!(op, Cmpop::Eq) {
-                checks.push(Check::new(
-                    CheckKind::NoneComparison(RejectedCmpop::Eq),
-                    locator.locate_check(Range::from_located(comparator)),
-                ));
-            }
-            if matches!(op, Cmpop::NotEq) {
-                checks.push(Check::new(
-                    CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                    locator.locate_check(Range::from_located(comparator)),
-                ));
-            }
-        }
-
-        if check_true_false_comparisons {
-            if let ExprKind::Constant {
-                value: Constant::Bool(value),
-                kind: None,
-            } = comparator.node
-            {
-                if matches!(op, Cmpop::Eq) {
-                    checks.push(Check::new(
-                        CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                        locator.locate_check(Range::from_located(comparator)),
-                    ));
-                }
-                if matches!(op, Cmpop::NotEq) {
-                    checks.push(Check::new(
-                        CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
-                        locator.locate_check(Range::from_located(comparator)),
-                    ));
-                }
-            }
-        }
-    }
-
-    checks
-}
-
-fn is_constant(expr: &Expr) -> bool {
-    match &expr.node {
-        ExprKind::Constant { .. } => true,
-        ExprKind::Tuple { elts, .. } => elts.iter().all(is_constant),
-        _ => false,
-    }
-}
-
-fn is_singleton(expr: &Expr) -> bool {
-    matches!(
-        expr.node,
-        ExprKind::Constant {
-            value: Constant::None | Constant::Bool(_) | Constant::Ellipsis,
-            ..
-        }
-    )
-}
-
-fn is_constant_non_singleton(expr: &Expr) -> bool {
-    is_constant(expr) && !is_singleton(expr)
-}
-
-/// Check IsLiteral compliance.
-pub fn check_is_literal(
-    left: &Expr,
-    ops: &Vec<Cmpop>,
-    comparators: &Vec<Expr>,
-    location: Range,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    let mut left = left;
-    for (op, right) in izip!(ops, comparators) {
-        if matches!(op, Cmpop::Is | Cmpop::IsNot)
-            && (is_constant_non_singleton(left) || is_constant_non_singleton(right))
-        {
-            checks.push(Check::new(CheckKind::IsLiteral, location));
-        }
-        left = right;
-    }
-
-    checks
-}
-
-/// Check TypeComparison compliance.
-pub fn check_type_comparison(
-    ops: &Vec<Cmpop>,
-    comparators: &Vec<Expr>,
-    location: Range,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    for (op, right) in izip!(ops, comparators) {
-        if matches!(op, Cmpop::Is | Cmpop::IsNot | Cmpop::Eq | Cmpop::NotEq) {
-            match &right.node {
-                ExprKind::Call { func, args, .. } => {
-                    if let ExprKind::Name { id, .. } = &func.node {
-                        // Ex) type(False)
-                        if id == "type" {
-                            if let Some(arg) = args.first() {
-                                // Allow comparison for types which are not obvious.
-                                if !matches!(arg.node, ExprKind::Name { .. }) {
-                                    checks.push(Check::new(CheckKind::TypeComparison, location));
-                                }
-                            }
-                        }
-                    }
-                }
-                ExprKind::Attribute { value, .. } => {
-                    if let ExprKind::Name { id, .. } = &value.node {
-                        // Ex) types.IntType
-                        if id == "types" {
-                            checks.push(Check::new(CheckKind::TypeComparison, location));
-                        }
-                    }
-                }
-                _ => {}
-            }
-        }
-    }
-
-    checks
-}
-
-/// Check TwoStarredExpressions and TooManyExpressionsInStarredAssignment compliance.
-pub fn check_starred_expressions(
-    elts: &[Expr],
-    check_too_many_expressions: bool,
-    check_two_starred_expressions: bool,
-    location: Range,
-) -> Option<Check> {
-    let mut has_starred: bool = false;
-    let mut starred_index: Option<usize> = None;
-    for (index, elt) in elts.iter().enumerate() {
-        if matches!(elt.node, ExprKind::Starred { .. }) {
-            if has_starred && check_two_starred_expressions {
-                return Some(Check::new(CheckKind::TwoStarredExpressions, location));
-            }
-            has_starred = true;
-            starred_index = Some(index);
-        }
-    }
-
-    if check_too_many_expressions {
-        if let Some(starred_index) = starred_index {
-            if starred_index >= 1 << 8 || elts.len() - starred_index > 1 << 24 {
-                return Some(Check::new(CheckKind::ExpressionsInStarAssignment, location));
-            }
-        }
-    }
-
-    None
-}
-
-/// Check BreakOutsideLoop compliance.
-pub fn check_break_outside_loop(
-    stmt: &Stmt,
-    parents: &[&Stmt],
-    parent_stack: &[usize],
-    locator: &dyn CheckLocator,
-) -> Option<Check> {
-    let mut allowed: bool = false;
-    let mut parent = stmt;
-    for index in parent_stack.iter().rev() {
-        let child = parent;
-        parent = parents[*index];
-        match &parent.node {
-            StmtKind::For { orelse, .. }
-            | StmtKind::AsyncFor { orelse, .. }
-            | StmtKind::While { orelse, .. } => {
-                if !orelse.contains(child) {
-                    allowed = true;
-                    break;
-                }
-            }
-
-            StmtKind::FunctionDef { .. }
-            | StmtKind::AsyncFunctionDef { .. }
-            | StmtKind::ClassDef { .. } => {
-                break;
-            }
-            _ => {}
-        }
-    }
-
-    if !allowed {
-        Some(Check::new(
-            CheckKind::BreakOutsideLoop,
-            locator.locate_check(Range::from_located(stmt)),
-        ))
-    } else {
-        None
-    }
-}
-
-/// Check ContinueOutsideLoop compliance.
-pub fn check_continue_outside_loop(
-    stmt: &Stmt,
-    parents: &[&Stmt],
-    parent_stack: &[usize],
-    locator: &dyn CheckLocator,
-) -> Option<Check> {
-    let mut allowed: bool = false;
-    let mut parent = stmt;
-    for index in parent_stack.iter().rev() {
-        let child = parent;
-        parent = parents[*index];
-        match &parent.node {
-            StmtKind::For { orelse, .. }
-            | StmtKind::AsyncFor { orelse, .. }
-            | StmtKind::While { orelse, .. } => {
-                if !orelse.contains(child) {
-                    allowed = true;
-                    break;
-                }
-            }
-
-            StmtKind::FunctionDef { .. }
-            | StmtKind::AsyncFunctionDef { .. }
-            | StmtKind::ClassDef { .. } => {
-                break;
-            }
-            _ => {}
-        }
-    }
-
-    if !allowed {
-        Some(Check::new(
-            CheckKind::ContinueOutsideLoop,
-            locator.locate_check(Range::from_located(stmt)),
-        ))
-    } else {
-        None
-    }
-}
-
-// flake8-builtins
-pub enum ShadowingType {
-    Variable,
-    Argument,
-    Attribute,
-}
-
-/// Check builtin name shadowing
-pub fn check_builtin_shadowing(
-    name: &str,
-    location: Range,
-    node_type: ShadowingType,
-) -> Option<Check> {
-    if BUILTINS.contains(&name) {
-        Some(Check::new(
-            match node_type {
-                ShadowingType::Variable => CheckKind::BuiltinVariableShadowing(name.to_string()),
-                ShadowingType::Argument => CheckKind::BuiltinArgumentShadowing(name.to_string()),
-                ShadowingType::Attribute => CheckKind::BuiltinAttributeShadowing(name.to_string()),
-            },
-            location,
-        ))
-    } else {
-        None
-    }
-}
-
-/// Returns `true` if a call is an argumented `super` invocation.
-pub fn is_super_call_with_arguments(func: &Expr, args: &Vec<Expr>) -> bool {
-    // Check: is this a `super` call?
-    if let ExprKind::Name { id, .. } = &func.node {
-        id == "super" && !args.is_empty()
-    } else {
-        false
-    }
-}
-
-// flakes8-comprehensions
-/// Check `list(generator)` compliance.
-pub fn unnecessary_generator_list(expr: &Expr, func: &Expr, args: &Vec<Expr>) -> Option<Check> {
-    if args.len() == 1 {
-        if let ExprKind::Name { id, .. } = &func.node {
-            if id == "list" {
-                if let ExprKind::GeneratorExp { .. } = &args[0].node {
-                    return Some(Check::new(
-                        CheckKind::UnnecessaryGeneratorList,
-                        Range::from_located(expr),
-                    ));
-                }
-            }
-        }
-    }
-    None
-}
-
-/// Check `set(generator)` compliance.
-pub fn unnecessary_generator_set(expr: &Expr, func: &Expr, args: &Vec<Expr>) -> Option<Check> {
-    if args.len() == 1 {
-        if let ExprKind::Name { id, .. } = &func.node {
-            if id == "set" {
-                if let ExprKind::GeneratorExp { .. } = &args[0].node {
-                    return Some(Check::new(
-                        CheckKind::UnnecessaryGeneratorList,
-                        Range::from_located(expr),
-                    ));
-                }
-            }
-        }
-    }
-    None
-}
-
-/// Check `set([...])` compliance.
-pub fn unnecessary_list_comprehension_set(
-    expr: &Expr,
-    func: &Expr,
-    args: &Vec<Expr>,
-) -> Option<Check> {
-    if args.len() == 1 {
-        if let ExprKind::Name { id, .. } = &func.node {
-            if id == "set" {
-                if let ExprKind::ListComp { .. } = &args[0].node {
-                    return Some(Check::new(
-                        CheckKind::UnnecessaryListComprehensionSet,
-                        Range::from_located(expr),
-                    ));
-                }
-            }
-        }
-    }
-    None
-}
-
-/// Check `dict([...])` compliance.
-pub fn unnecessary_list_comprehension_dict(
-    expr: &Expr,
-    func: &Expr,
-    args: &Vec<Expr>,
-) -> Option<Check> {
-    if args.len() == 1 {
-        if let ExprKind::Name { id, .. } = &func.node {
-            if id == "dict" {
-                if let ExprKind::ListComp { elt, .. } = &args[0].node {
-                    match &elt.node {
-                        ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
-                            return Some(Check::new(
-                                CheckKind::UnnecessaryListComprehensionDict,
-                                Range::from_located(expr),
-                            ));
-                        }
-                        _ => {}
-                    }
-                }
-            }
-        }
-    }
-    None
-}
-
-// flake8-super
-/// Check that `super()` has no args
-pub fn check_super_args(
-    scope: &Scope,
-    parents: &[&Stmt],
-    expr: &Expr,
-    func: &Expr,
-    args: &Vec<Expr>,
-) -> Option<Check> {
-    if !is_super_call_with_arguments(func, args) {
-        return None;
-    }
-
-    // Check: are we in a Function scope?
-    if !matches!(scope.kind, ScopeKind::Function { .. }) {
-        return None;
-    }
-
-    let mut parents = parents.iter().rev();
-
-    // For a `super` invocation to be unnecessary, the first argument needs to match the enclosing
-    // class, and the second argument needs to match the first argument to the enclosing function.
-    if let [first_arg, second_arg] = args.as_slice() {
-        // Find the enclosing function definition (if any).
-        if let Some(StmtKind::FunctionDef {
-            args: parent_args, ..
-        }) = parents
-            .find(|stmt| matches!(stmt.node, StmtKind::FunctionDef { .. }))
-            .map(|stmt| &stmt.node)
-        {
-            // Extract the name of the first argument to the enclosing function.
-            if let Some(ArgData {
-                arg: parent_arg, ..
-            }) = parent_args.args.first().map(|expr| &expr.node)
-            {
-                // Find the enclosing class definition (if any).
-                if let Some(StmtKind::ClassDef {
-                    name: parent_name, ..
-                }) = parents
-                    .find(|stmt| matches!(stmt.node, StmtKind::ClassDef { .. }))
-                    .map(|stmt| &stmt.node)
-                {
-                    if let (
-                        ExprKind::Name {
-                            id: first_arg_id, ..
-                        },
-                        ExprKind::Name {
-                            id: second_arg_id, ..
-                        },
-                    ) = (&first_arg.node, &second_arg.node)
-                    {
-                        if first_arg_id == parent_name && second_arg_id == parent_arg {
-                            return Some(Check::new(
-                                CheckKind::SuperCallWithParameters,
-                                Range::from_located(expr),
-                            ));
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    None
-}
-
-// flake8-print
-/// Check whether a function call is a `print` or `pprint` invocation
-pub fn check_print_call(
-    expr: &Expr,
-    func: &Expr,
-    check_print: bool,
-    check_pprint: bool,
-) -> Option<Check> {
-    if let ExprKind::Name { id, .. } = &func.node {
-        if check_print && id == "print" {
-            return Some(Check::new(CheckKind::PrintFound, Range::from_located(expr)));
-        } else if check_pprint && id == "pprint" {
-            return Some(Check::new(
-                CheckKind::PPrintFound,
-                Range::from_located(expr),
-            ));
-        }
-    }
-
-    if let ExprKind::Attribute { value, attr, .. } = &func.node {
-        if let ExprKind::Name { id, .. } = &value.node {
-            if check_pprint && id == "pprint" && attr == "pprint" {
-                return Some(Check::new(
-                    CheckKind::PPrintFound,
-                    Range::from_located(expr),
-                ));
-            }
-        }
-    }
-
-    None
-}

src/ast/helpers.rs

@@ -0,0 +1,145 @@
+use once_cell::sync::Lazy;
+use regex::Regex;
+use rustpython_ast::{Excepthandler, ExcepthandlerKind, Expr, ExprKind, Location, StmtKind};
+
+use crate::python::typing;
+
+fn compose_call_path_inner<'a>(expr: &'a Expr, parts: &mut Vec<&'a str>) {
+    match &expr.node {
+        ExprKind::Call { func, .. } => {
+            compose_call_path_inner(func, parts);
+        }
+        ExprKind::Attribute { value, attr, .. } => {
+            compose_call_path_inner(value, parts);
+            parts.push(attr);
+        }
+        ExprKind::Name { id, .. } => {
+            parts.push(id);
+        }
+        _ => {}
+    }
+}
+
+pub fn compose_call_path(expr: &Expr) -> Option<String> {
+    let mut segments = vec![];
+    compose_call_path_inner(expr, &mut segments);
+    if segments.is_empty() {
+        None
+    } else {
+        Some(segments.join("."))
+    }
+}
+
+pub fn match_name_or_attr(expr: &Expr, target: &str) -> bool {
+    match &expr.node {
+        ExprKind::Attribute { attr, .. } => target == attr,
+        ExprKind::Name { id, .. } => target == id,
+        _ => false,
+    }
+}
+
+pub enum SubscriptKind {
+    AnnotatedSubscript,
+    PEP593AnnotatedSubscript,
+}
+
+pub fn match_annotated_subscript(expr: &Expr) -> Option<SubscriptKind> {
+    match &expr.node {
+        ExprKind::Attribute { attr, .. } => {
+            if typing::is_annotated_subscript(attr) {
+                Some(SubscriptKind::AnnotatedSubscript)
+            } else if typing::is_pep593_annotated_subscript(attr) {
+                Some(SubscriptKind::PEP593AnnotatedSubscript)
+            } else {
+                None
+            }
+        }
+        ExprKind::Name { id, .. } => {
+            if typing::is_annotated_subscript(id) {
+                Some(SubscriptKind::AnnotatedSubscript)
+            } else if typing::is_pep593_annotated_subscript(id) {
+                Some(SubscriptKind::PEP593AnnotatedSubscript)
+            } else {
+                None
+            }
+        }
+        _ => None,
+    }
+}
+
+static DUNDER_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"__[^\s]+__").unwrap());
+
+pub fn is_assignment_to_a_dunder(node: &StmtKind) -> bool {
+    // Check whether it's an assignment to a dunder, with or without a type annotation.
+    // This is what pycodestyle (as of 2.9.1) does.
+    match node {
+        StmtKind::Assign {
+            targets,
+            value: _,
+            type_comment: _,
+        } => {
+            if targets.len() != 1 {
+                return false;
+            }
+            match &targets[0].node {
+                ExprKind::Name { id, ctx: _ } => DUNDER_REGEX.is_match(id),
+                _ => false,
+            }
+        }
+        StmtKind::AnnAssign {
+            target,
+            annotation: _,
+            value: _,
+            simple: _,
+        } => match &target.node {
+            ExprKind::Name { id, ctx: _ } => DUNDER_REGEX.is_match(id),
+            _ => false,
+        },
+        _ => false,
+    }
+}
+
+/// Extract the names of all handled exceptions.
+pub fn extract_handler_names(handlers: &[Excepthandler]) -> Vec<String> {
+    let mut handler_names = vec![];
+    for handler in handlers {
+        match &handler.node {
+            ExcepthandlerKind::ExceptHandler { type_, .. } => {
+                if let Some(type_) = type_ {
+                    if let ExprKind::Tuple { elts, .. } = &type_.node {
+                        for type_ in elts {
+                            if let Some(name) = compose_call_path(type_) {
+                                handler_names.push(name);
+                            }
+                        }
+                    } else if let Some(name) = compose_call_path(type_) {
+                        handler_names.push(name);
+                    }
+                }
+            }
+        }
+    }
+    handler_names
+}
+
+/// Returns `true` if a call is an argumented `super` invocation.
+pub fn is_super_call_with_arguments(func: &Expr, args: &[Expr]) -> bool {
+    // Check: is this a `super` call?
+    if let ExprKind::Name { id, .. } = &func.node {
+        id == "super" && !args.is_empty()
+    } else {
+        false
+    }
+}
+
+/// Convert a location within a file (relative to `base`) to an absolute position.
+pub fn to_absolute(relative: &Location, base: &Location) -> Location {
+    if relative.row() == 1 {
+        Location::new(
+            relative.row() + base.row() - 1,
+            relative.column() + base.column() - 1,
+        )
+    } else {
+        Location::new(relative.row() + base.row() - 1, relative.column())
+    }
+}

src/ast/operations.rs

@@ -121,7 +121,7 @@ pub fn is_unpacking_assignment(stmt: &Stmt) -> bool {
 /// Struct used to efficiently slice source code at (row, column) Locations.
 pub struct SourceCodeLocator<'a> {
     content: &'a str,
-    offsets: Vec<usize>,
+    offsets: Vec<Vec<usize>>,
     initialized: bool,
 }
 
@@ -134,32 +134,52 @@ impl<'a> SourceCodeLocator<'a> {
         }
     }
 
-    pub fn slice_source_code_at(&mut self, location: &Location) -> &'a str {
+    fn init(&mut self) {
         if !self.initialized {
             let mut offset = 0;
-            for i in self.content.lines() {
-                self.offsets.push(offset);
-                offset += i.len();
-                offset += 1;
+            for line in self.content.lines() {
+                let mut newline = 0;
+                let mut line_offsets: Vec<usize> = vec![];
+                for (i, _char) in line.char_indices() {
+                    line_offsets.push(offset + i);
+                    newline = i + 1;
+                }
+                line_offsets.push(offset + newline);
+                self.offsets.push(line_offsets);
+                offset += newline + 1;
             }
+            self.offsets.push(vec![offset]);
             self.initialized = true;
         }
-        let offset = self.offsets[location.row() - 1] + location.column() - 1;
+    }
+
+    pub fn slice_source_code_at(&mut self, location: &Location) -> &'a str {
+        self.init();
+        let offset = self.offsets[location.row() - 1][location.column() - 1];
         &self.content[offset..]
     }
 
     pub fn slice_source_code_range(&mut self, range: &Range) -> &'a str {
-        if !self.initialized {
-            let mut offset = 0;
-            for i in self.content.lines() {
-                self.offsets.push(offset);
-                offset += i.len();
-                offset += 1;
-            }
-            self.initialized = true;
-        }
-        let start = self.offsets[range.location.row() - 1] + range.location.column() - 1;
-        let end = self.offsets[range.end_location.row() - 1] + range.end_location.column() - 1;
+        self.init();
+        let start = self.offsets[range.location.row() - 1][range.location.column() - 1];
+        let end = self.offsets[range.end_location.row() - 1][range.end_location.column() - 1];
         &self.content[start..end]
     }
+
+    pub fn partition_source_code_at(
+        &mut self,
+        outer: &Range,
+        inner: &Range,
+    ) -> (&'a str, &'a str, &'a str) {
+        self.init();
+        let outer_start = self.offsets[outer.location.row() - 1][outer.location.column() - 1];
+        let outer_end = self.offsets[outer.end_location.row() - 1][outer.end_location.column() - 1];
+        let inner_start = self.offsets[inner.location.row() - 1][inner.location.column() - 1];
+        let inner_end = self.offsets[inner.end_location.row() - 1][inner.end_location.column() - 1];
+        (
+            &self.content[outer_start..inner_start],
+            &self.content[inner_start..inner_end],
+            &self.content[inner_end..outer_end],
+        )
+    }
 }

src/ast/relocate.rs

@@ -4,14 +4,14 @@ use crate::ast::types::Range;
 
 fn relocate_keyword(keyword: &mut Keyword, location: Range) {
     keyword.location = location.location;
-    keyword.end_location = location.end_location;
+    keyword.end_location = Some(location.end_location);
     relocate_expr(&mut keyword.node.value, location);
 }
 
 /// Change an expression's location (recursively) to match a desired, fixed location.
 pub fn relocate_expr(expr: &mut Expr, location: Range) {
     expr.location = location.location;
-    expr.end_location = location.end_location;
+    expr.end_location = Some(location.end_location);
     match &mut expr.node {
         ExprKind::BoolOp { values, .. } => {
             for expr in values {

src/ast/types.rs

@@ -18,7 +18,9 @@ impl Range {
     pub fn from_located<T>(located: &Located<T>) -> Self {
         Range {
             location: located.location,
-            end_location: located.end_location,
+            end_location: located
+                .end_location
+                .expect("AST nodes should have end_location."),
         }
     }
 }
@@ -74,9 +76,9 @@ pub enum BindingKind {
     Export(Vec<String>),
     FutureImportation,
     StarImportation,
-    Importation(String, BindingContext),
-    FromImportation(String, BindingContext),
-    SubmoduleImportation(String, BindingContext),
+    Importation(String, String, BindingContext),
+    FromImportation(String, String, BindingContext),
+    SubmoduleImportation(String, String, BindingContext),
 }
 
 #[derive(Clone, Debug)]

src/ast/visitor.rs

@@ -4,6 +4,8 @@ use rustpython_parser::ast::{
     PatternKind, Stmt, StmtKind, Unaryop, Withitem,
 };
 
+use crate::ast::helpers::match_name_or_attr;
+
 pub trait Visitor<'a> {
     fn visit_stmt(&mut self, stmt: &'a Stmt) {
         walk_stmt(self, stmt);
@@ -148,7 +150,11 @@ pub fn walk_stmt<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, stmt: &'a Stmt) {
         } => {
             visitor.visit_annotation(annotation);
             if let Some(expr) = value {
-                visitor.visit_expr(expr);
+                if match_name_or_attr(annotation, "TypeAlias") {
+                    visitor.visit_annotation(expr);
+                } else {
+                    visitor.visit_expr(expr);
+                }
             }
             visitor.visit_expr(target);
         }

src/autofix.rs

@@ -1,2 +0,0 @@
-pub mod fixer;
-pub mod fixes;

src/autofix/fixer.rs

@@ -1,11 +1,10 @@
-use std::fs;
-use std::path::Path;
-
-use anyhow::Result;
+use crate::autofix::Fix;
+use crate::autofix::Patch;
 use itertools::Itertools;
 use rustpython_parser::ast::Location;
+use std::collections::BTreeSet;
 
-use crate::checks::{Check, Fix};
+use crate::checks::Check;
 
 #[derive(Hash)]
 pub enum Mode {
@@ -24,51 +23,59 @@ impl From<bool> for Mode {
 }
 
 /// Auto-fix errors in a file, and write the fixed source code to disk.
-pub fn fix_file(checks: &mut [Check], contents: &str, path: &Path) -> Result<()> {
+pub fn fix_file(checks: &mut [Check], contents: &str) -> Option<String> {
     if checks.iter().all(|check| check.fix.is_none()) {
-        return Ok(());
+        return None;
     }
 
-    let output = apply_fixes(
+    Some(apply_fixes(
         checks.iter_mut().filter_map(|check| check.fix.as_mut()),
         contents,
-    );
-
-    fs::write(path, output).map_err(|e| e.into())
+    ))
 }
 
 /// Apply a series of fixes.
 fn apply_fixes<'a>(fixes: impl Iterator<Item = &'a mut Fix>, contents: &str) -> String {
     let lines: Vec<&str> = contents.lines().collect();
 
-    let mut output = "".to_string();
-    let mut last_pos: Location = Location::new(0, 0);
+    let mut output: String = Default::default();
+    let mut last_pos: Location = Default::default();
+    let mut applied: BTreeSet<&Patch> = Default::default();
 
-    for fix in fixes.sorted_by_key(|fix| fix.location) {
-        // Best-effort approach: if this fix overlaps with a fix we've already applied, skip it.
-        if last_pos > fix.location {
+    for fix in fixes.sorted_by_key(|fix| fix.patch.location) {
+        // If we already applied an identical fix as part of another correction, skip any
+        // re-application.
+        if applied.contains(&fix.patch) {
+            fix.applied = true;
             continue;
         }
 
-        if fix.location.row() > last_pos.row() {
+        // Best-effort approach: if this fix overlaps with a fix we've already applied, skip it.
+        if last_pos > fix.patch.location {
+            continue;
+        }
+
+        if fix.patch.location.row() > last_pos.row() {
             if last_pos.row() > 0 || last_pos.column() > 0 {
                 output.push_str(&lines[last_pos.row() - 1][last_pos.column() - 1..]);
                 output.push('\n');
             }
-            for line in &lines[last_pos.row()..fix.location.row() - 1] {
+            for line in &lines[last_pos.row()..fix.patch.location.row() - 1] {
                 output.push_str(line);
                 output.push('\n');
             }
-            output.push_str(&lines[fix.location.row() - 1][..fix.location.column() - 1]);
-            output.push_str(&fix.content);
+            output
+                .push_str(&lines[fix.patch.location.row() - 1][..fix.patch.location.column() - 1]);
+            output.push_str(&fix.patch.content);
         } else {
             output.push_str(
-                &lines[last_pos.row() - 1][last_pos.column() - 1..fix.location.column() - 1],
+                &lines[last_pos.row() - 1][last_pos.column() - 1..fix.patch.location.column() - 1],
             );
-            output.push_str(&fix.content);
+            output.push_str(&fix.patch.content);
         }
+        last_pos = fix.patch.end_location;
 
-        last_pos = fix.end_location;
+        applied.insert(&fix.patch);
         fix.applied = true;
     }
 
@@ -95,7 +102,8 @@ mod tests {
     use rustpython_parser::ast::Location;
 
     use crate::autofix::fixer::apply_fixes;
-    use crate::checks::Fix;
+    use crate::autofix::Fix;
+    use crate::autofix::Patch;
 
     #[test]
     fn empty_file() -> Result<()> {
@@ -111,9 +119,11 @@ mod tests {
     #[test]
     fn apply_single_replacement() -> Result<()> {
         let mut fixes = vec![Fix {
-            content: "Bar".to_string(),
-            location: Location::new(1, 9),
-            end_location: Location::new(1, 15),
+            patch: Patch {
+                content: "Bar".to_string(),
+                location: Location::new(1, 9),
+                end_location: Location::new(1, 15),
+            },
             applied: false,
         }];
         let actual = apply_fixes(
@@ -135,9 +145,11 @@ mod tests {
     #[test]
     fn apply_single_removal() -> Result<()> {
         let mut fixes = vec![Fix {
-            content: "".to_string(),
-            location: Location::new(1, 8),
-            end_location: Location::new(1, 16),
+            patch: Patch {
+                content: "".to_string(),
+                location: Location::new(1, 8),
+                end_location: Location::new(1, 16),
+            },
             applied: false,
         }];
         let actual = apply_fixes(
@@ -160,15 +172,19 @@ mod tests {
     fn apply_double_removal() -> Result<()> {
         let mut fixes = vec![
             Fix {
-                content: "".to_string(),
-                location: Location::new(1, 8),
-                end_location: Location::new(1, 17),
+                patch: Patch {
+                    content: "".to_string(),
+                    location: Location::new(1, 8),
+                    end_location: Location::new(1, 17),
+                },
                 applied: false,
             },
             Fix {
-                content: "".to_string(),
-                location: Location::new(1, 17),
-                end_location: Location::new(1, 24),
+                patch: Patch {
+                    content: "".to_string(),
+                    location: Location::new(1, 17),
+                    end_location: Location::new(1, 24),
+                },
                 applied: false,
             },
         ];
@@ -192,15 +208,19 @@ mod tests {
     fn ignore_overlapping_fixes() -> Result<()> {
         let mut fixes = vec![
             Fix {
-                content: "".to_string(),
-                location: Location::new(1, 8),
-                end_location: Location::new(1, 16),
+                patch: Patch {
+                    content: "".to_string(),
+                    location: Location::new(1, 8),
+                    end_location: Location::new(1, 16),
+                },
                 applied: false,
             },
             Fix {
-                content: "ignored".to_string(),
-                location: Location::new(1, 10),
-                end_location: Location::new(1, 12),
+                patch: Patch {
+                    content: "ignored".to_string(),
+                    location: Location::new(1, 10),
+                    end_location: Location::new(1, 12),
+                },
                 applied: false,
             },
         ];

src/autofix/fixes.rs

@@ -1,392 +0,0 @@
-use anyhow::Result;
-use itertools::Itertools;
-use libcst_native::ImportNames::Aliases;
-use libcst_native::NameOrAttribute::N;
-use libcst_native::{Codegen, Expression, SmallStatement, Statement};
-use rustpython_parser::ast::{ExcepthandlerKind, Expr, Keyword, Location, Stmt, StmtKind};
-use rustpython_parser::lexer;
-use rustpython_parser::token::Tok;
-
-use crate::ast::operations::SourceCodeLocator;
-use crate::ast::types::Range;
-use crate::checks::Fix;
-
-/// Convert a location within a file (relative to `base`) to an absolute position.
-fn to_absolute(relative: &Location, base: &Location) -> Location {
-    if relative.row() == 1 {
-        Location::new(
-            relative.row() + base.row() - 1,
-            relative.column() + base.column() - 1,
-        )
-    } else {
-        Location::new(relative.row() + base.row() - 1, relative.column())
-    }
-}
-
-/// Generate a fix to remove a base from a ClassDef statement.
-pub fn remove_class_def_base(
-    locator: &mut SourceCodeLocator,
-    stmt_at: &Location,
-    expr_at: Location,
-    bases: &[Expr],
-    keywords: &[Keyword],
-) -> Option<Fix> {
-    let content = locator.slice_source_code_at(stmt_at);
-
-    // Case 1: `object` is the only base.
-    if bases.len() == 1 && keywords.is_empty() {
-        let mut fix_start = None;
-        let mut fix_end = None;
-        let mut count: usize = 0;
-        for (start, tok, end) in lexer::make_tokenizer(content).flatten() {
-            if matches!(tok, Tok::Lpar) {
-                if count == 0 {
-                    fix_start = Some(to_absolute(&start, stmt_at));
-                }
-                count += 1;
-            }
-
-            if matches!(tok, Tok::Rpar) {
-                count -= 1;
-                if count == 0 {
-                    fix_end = Some(to_absolute(&end, stmt_at));
-                    break;
-                }
-            }
-        }
-
-        return match (fix_start, fix_end) {
-            (Some(start), Some(end)) => Some(Fix {
-                content: "".to_string(),
-                location: start,
-                end_location: end,
-                applied: false,
-            }),
-            _ => None,
-        };
-    }
-
-    if bases
-        .iter()
-        .map(|node| node.location)
-        .chain(keywords.iter().map(|node| node.location))
-        .any(|location| location > expr_at)
-    {
-        // Case 2: `object` is _not_ the last node.
-        let mut fix_start: Option<Location> = None;
-        let mut fix_end: Option<Location> = None;
-        let mut seen_comma = false;
-        for (start, tok, end) in lexer::make_tokenizer(content).flatten() {
-            let start = to_absolute(&start, stmt_at);
-            if seen_comma {
-                if matches!(tok, Tok::Newline) {
-                    fix_end = Some(end);
-                } else {
-                    fix_end = Some(start);
-                }
-                break;
-            }
-            if start == expr_at {
-                fix_start = Some(start);
-            }
-            if fix_start.is_some() && matches!(tok, Tok::Comma) {
-                seen_comma = true;
-            }
-        }
-
-        match (fix_start, fix_end) {
-            (Some(start), Some(end)) => Some(Fix {
-                content: "".to_string(),
-                location: start,
-                end_location: end,
-                applied: false,
-            }),
-            _ => None,
-        }
-    } else {
-        // Case 3: `object` is the last node, so we have to find the last token that isn't a comma.
-        let mut fix_start: Option<Location> = None;
-        let mut fix_end: Option<Location> = None;
-        for (start, tok, end) in lexer::make_tokenizer(content).flatten() {
-            let start = to_absolute(&start, stmt_at);
-            let end = to_absolute(&end, stmt_at);
-            if start == expr_at {
-                fix_end = Some(end);
-                break;
-            }
-            if matches!(tok, Tok::Comma) {
-                fix_start = Some(start);
-            }
-        }
-
-        match (fix_start, fix_end) {
-            (Some(start), Some(end)) => Some(Fix {
-                content: "".to_string(),
-                location: start,
-                end_location: end,
-                applied: false,
-            }),
-            _ => None,
-        }
-    }
-}
-
-pub fn remove_super_arguments(locator: &mut SourceCodeLocator, expr: &Expr) -> Option<Fix> {
-    let range = Range::from_located(expr);
-    let contents = locator.slice_source_code_range(&range);
-
-    let mut tree = match libcst_native::parse_module(contents, None) {
-        Ok(m) => m,
-        Err(_) => return None,
-    };
-
-    if let Some(Statement::Simple(body)) = tree.body.first_mut() {
-        if let Some(SmallStatement::Expr(body)) = body.body.first_mut() {
-            if let Expression::Call(body) = &mut body.value {
-                body.args = vec![];
-                body.whitespace_before_args = Default::default();
-                body.whitespace_after_func = Default::default();
-
-                let mut state = Default::default();
-                tree.codegen(&mut state);
-
-                return Some(Fix {
-                    content: state.to_string(),
-                    location: range.location,
-                    end_location: range.end_location,
-                    applied: false,
-                });
-            }
-        }
-    }
-
-    None
-}
-
-/// Determine if a body contains only a single statement, taking into account deleted.
-fn has_single_child(body: &[Stmt], deleted: &[&Stmt]) -> bool {
-    body.iter().filter(|child| !deleted.contains(child)).count() == 1
-}
-
-/// Determine if a child is the only statement in its body.
-fn is_lone_child(child: &Stmt, parent: &Stmt, deleted: &[&Stmt]) -> Result<bool> {
-    match &parent.node {
-        StmtKind::FunctionDef { body, .. }
-        | StmtKind::AsyncFunctionDef { body, .. }
-        | StmtKind::ClassDef { body, .. }
-        | StmtKind::With { body, .. }
-        | StmtKind::AsyncWith { body, .. } => {
-            if body.iter().contains(child) {
-                Ok(has_single_child(body, deleted))
-            } else {
-                Err(anyhow::anyhow!("Unable to find child in parent body."))
-            }
-        }
-        StmtKind::For { body, orelse, .. }
-        | StmtKind::AsyncFor { body, orelse, .. }
-        | StmtKind::While { body, orelse, .. }
-        | StmtKind::If { body, orelse, .. } => {
-            if body.iter().contains(child) {
-                Ok(has_single_child(body, deleted))
-            } else if orelse.iter().contains(child) {
-                Ok(has_single_child(orelse, deleted))
-            } else {
-                Err(anyhow::anyhow!("Unable to find child in parent body."))
-            }
-        }
-        StmtKind::Try {
-            body,
-            handlers,
-            orelse,
-            finalbody,
-        } => {
-            if body.iter().contains(child) {
-                Ok(has_single_child(body, deleted))
-            } else if orelse.iter().contains(child) {
-                Ok(has_single_child(orelse, deleted))
-            } else if finalbody.iter().contains(child) {
-                Ok(has_single_child(finalbody, deleted))
-            } else if let Some(body) = handlers.iter().find_map(|handler| match &handler.node {
-                ExcepthandlerKind::ExceptHandler { body, .. } => {
-                    if body.iter().contains(child) {
-                        Some(body)
-                    } else {
-                        None
-                    }
-                }
-            }) {
-                Ok(has_single_child(body, deleted))
-            } else {
-                Err(anyhow::anyhow!("Unable to find child in parent body."))
-            }
-        }
-        _ => Err(anyhow::anyhow!("Unable to find child in parent body.")),
-    }
-}
-
-pub fn remove_stmt(stmt: &Stmt, parent: Option<&Stmt>, deleted: &[&Stmt]) -> Result<Fix> {
-    if parent
-        .map(|parent| is_lone_child(stmt, parent, deleted))
-        .map_or(Ok(None), |v| v.map(Some))?
-        .unwrap_or_default()
-    {
-        // If removing this node would lead to an invalid syntax tree, replace
-        // it with a `pass`.
-        Ok(Fix {
-            location: stmt.location,
-            end_location: stmt.end_location,
-            content: "pass".to_string(),
-            applied: false,
-        })
-    } else {
-        // Otherwise, nuke the entire line.
-        // TODO(charlie): This logic assumes that there are no multi-statement physical lines.
-        Ok(Fix {
-            location: Location::new(stmt.location.row(), 1),
-            end_location: Location::new(stmt.end_location.row() + 1, 1),
-            content: "".to_string(),
-            applied: false,
-        })
-    }
-}
-
-/// Generate a Fix to remove any unused imports from an `import` statement.
-pub fn remove_unused_imports(
-    locator: &mut SourceCodeLocator,
-    full_names: &[&str],
-    stmt: &Stmt,
-    parent: Option<&Stmt>,
-    deleted: &[&Stmt],
-) -> Result<Fix> {
-    let mut tree = match libcst_native::parse_module(
-        locator.slice_source_code_range(&Range::from_located(stmt)),
-        None,
-    ) {
-        Ok(m) => m,
-        Err(_) => return Err(anyhow::anyhow!("Failed to extract CST from source.")),
-    };
-
-    let body = if let Some(Statement::Simple(body)) = tree.body.first_mut() {
-        body
-    } else {
-        return Err(anyhow::anyhow!("Expected node to be: Statement::Simple."));
-    };
-    let body = if let Some(SmallStatement::Import(body)) = body.body.first_mut() {
-        body
-    } else {
-        return Err(anyhow::anyhow!(
-            "Expected node to be: SmallStatement::ImportFrom."
-        ));
-    };
-    let aliases = &mut body.names;
-
-    // Preserve the trailing comma (or not) from the last entry.
-    let trailing_comma = aliases.last().and_then(|alias| alias.comma.clone());
-
-    // Identify unused imports from within the `import from`.
-    let mut removable = vec![];
-    for (index, alias) in aliases.iter().enumerate() {
-        if let N(import_name) = &alias.name {
-            if full_names.contains(&import_name.value) {
-                removable.push(index);
-            }
-        }
-    }
-    // TODO(charlie): This is quadratic.
-    for index in removable.iter().rev() {
-        aliases.remove(*index);
-    }
-
-    if let Some(alias) = aliases.last_mut() {
-        alias.comma = trailing_comma;
-    }
-
-    if aliases.is_empty() {
-        remove_stmt(stmt, parent, deleted)
-    } else {
-        let mut state = Default::default();
-        tree.codegen(&mut state);
-
-        Ok(Fix {
-            content: state.to_string(),
-            location: stmt.location,
-            end_location: stmt.end_location,
-            applied: false,
-        })
-    }
-}
-
-/// Generate a Fix to remove any unused imports from an `import from` statement.
-pub fn remove_unused_import_froms(
-    locator: &mut SourceCodeLocator,
-    full_names: &[&str],
-    stmt: &Stmt,
-    parent: Option<&Stmt>,
-    deleted: &[&Stmt],
-) -> Result<Fix> {
-    let mut tree = match libcst_native::parse_module(
-        locator.slice_source_code_range(&Range::from_located(stmt)),
-        None,
-    ) {
-        Ok(m) => m,
-        Err(_) => return Err(anyhow::anyhow!("Failed to extract CST from source.")),
-    };
-
-    let body = if let Some(Statement::Simple(body)) = tree.body.first_mut() {
-        body
-    } else {
-        return Err(anyhow::anyhow!("Expected node to be: Statement::Simple."));
-    };
-    let body = if let Some(SmallStatement::ImportFrom(body)) = body.body.first_mut() {
-        body
-    } else {
-        return Err(anyhow::anyhow!(
-            "Expected node to be: SmallStatement::ImportFrom."
-        ));
-    };
-    let aliases = if let Aliases(aliases) = &mut body.names {
-        aliases
-    } else {
-        return Err(anyhow::anyhow!("Expected node to be: Aliases."));
-    };
-
-    // Preserve the trailing comma (or not) from the last entry.
-    let trailing_comma = aliases.last().and_then(|alias| alias.comma.clone());
-
-    // Identify unused imports from within the `import from`.
-    let mut removable = vec![];
-    for (index, alias) in aliases.iter().enumerate() {
-        if let N(name) = &alias.name {
-            let import_name = if let Some(N(module_name)) = &body.module {
-                format!("{}.{}", module_name.value, name.value)
-            } else {
-                name.value.to_string()
-            };
-            if full_names.contains(&import_name.as_str()) {
-                removable.push(index);
-            }
-        }
-    }
-    // TODO(charlie): This is quadratic.
-    for index in removable.iter().rev() {
-        aliases.remove(*index);
-    }
-
-    if let Some(alias) = aliases.last_mut() {
-        alias.comma = trailing_comma;
-    }
-
-    if aliases.is_empty() {
-        remove_stmt(stmt, parent, deleted)
-    } else {
-        let mut state = Default::default();
-        tree.codegen(&mut state);
-
-        Ok(Fix {
-            content: state.to_string(),
-            location: stmt.location,
-            end_location: stmt.end_location,
-            applied: false,
-        })
-    }
-}

src/autofix/helpers.rs

@@ -0,0 +1,89 @@
+use anyhow::Result;
+use itertools::Itertools;
+use rustpython_parser::ast::{ExcepthandlerKind, Location, Stmt, StmtKind};
+
+use crate::autofix::Fix;
+
+/// Determine if a body contains only a single statement, taking into account deleted.
+fn has_single_child(body: &[Stmt], deleted: &[&Stmt]) -> bool {
+    body.iter().filter(|child| !deleted.contains(child)).count() == 1
+}
+
+/// Determine if a child is the only statement in its body.
+fn is_lone_child(child: &Stmt, parent: &Stmt, deleted: &[&Stmt]) -> Result<bool> {
+    match &parent.node {
+        StmtKind::FunctionDef { body, .. }
+        | StmtKind::AsyncFunctionDef { body, .. }
+        | StmtKind::ClassDef { body, .. }
+        | StmtKind::With { body, .. }
+        | StmtKind::AsyncWith { body, .. } => {
+            if body.iter().contains(child) {
+                Ok(has_single_child(body, deleted))
+            } else {
+                Err(anyhow::anyhow!("Unable to find child in parent body."))
+            }
+        }
+        StmtKind::For { body, orelse, .. }
+        | StmtKind::AsyncFor { body, orelse, .. }
+        | StmtKind::While { body, orelse, .. }
+        | StmtKind::If { body, orelse, .. } => {
+            if body.iter().contains(child) {
+                Ok(has_single_child(body, deleted))
+            } else if orelse.iter().contains(child) {
+                Ok(has_single_child(orelse, deleted))
+            } else {
+                Err(anyhow::anyhow!("Unable to find child in parent body."))
+            }
+        }
+        StmtKind::Try {
+            body,
+            handlers,
+            orelse,
+            finalbody,
+        } => {
+            if body.iter().contains(child) {
+                Ok(has_single_child(body, deleted))
+            } else if orelse.iter().contains(child) {
+                Ok(has_single_child(orelse, deleted))
+            } else if finalbody.iter().contains(child) {
+                Ok(has_single_child(finalbody, deleted))
+            } else if let Some(body) = handlers.iter().find_map(|handler| match &handler.node {
+                ExcepthandlerKind::ExceptHandler { body, .. } => {
+                    if body.iter().contains(child) {
+                        Some(body)
+                    } else {
+                        None
+                    }
+                }
+            }) {
+                Ok(has_single_child(body, deleted))
+            } else {
+                Err(anyhow::anyhow!("Unable to find child in parent body."))
+            }
+        }
+        _ => Err(anyhow::anyhow!("Unable to find child in parent body.")),
+    }
+}
+
+pub fn remove_stmt(stmt: &Stmt, parent: Option<&Stmt>, deleted: &[&Stmt]) -> Result<Fix> {
+    if parent
+        .map(|parent| is_lone_child(stmt, parent, deleted))
+        .map_or(Ok(None), |v| v.map(Some))?
+        .unwrap_or_default()
+    {
+        // If removing this node would lead to an invalid syntax tree, replace
+        // it with a `pass`.
+        Ok(Fix::replacement(
+            "pass".to_string(),
+            stmt.location,
+            stmt.end_location.unwrap(),
+        ))
+    } else {
+        // Otherwise, nuke the entire line.
+        // TODO(charlie): This logic assumes that there are no multi-statement physical lines.
+        Ok(Fix::deletion(
+            Location::new(stmt.location.row(), 1),
+            Location::new(stmt.end_location.unwrap().row() + 1, 1),
+        ))
+    }
+}

src/autofix/mod.rs

@@ -0,0 +1,53 @@
+use rustpython_ast::Location;
+use serde::{Deserialize, Serialize};
+
+pub mod fixer;
+pub mod helpers;
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
+pub struct Patch {
+    pub content: String,
+    pub location: Location,
+    pub end_location: Location,
+}
+
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Fix {
+    pub patch: Patch,
+    pub applied: bool,
+}
+
+impl Fix {
+    pub fn deletion(start: Location, end: Location) -> Self {
+        Self {
+            patch: Patch {
+                content: "".to_string(),
+                location: start,
+                end_location: end,
+            },
+            applied: false,
+        }
+    }
+
+    pub fn replacement(content: String, start: Location, end: Location) -> Self {
+        Self {
+            patch: Patch {
+                content,
+                location: start,
+                end_location: end,
+            },
+            applied: false,
+        }
+    }
+
+    pub fn insertion(content: String, at: Location) -> Self {
+        Self {
+            patch: Patch {
+                content,
+                location: at,
+                end_location: at,
+            },
+            applied: false,
+        }
+    }
+}

src/cache.rs

@@ -1,3 +1,9 @@
+// cacache uses asyncd-std which has no wasm support, so currently no caching support on wasm
+#![cfg_attr(
+    target_family = "wasm",
+    allow(unused_imports, unused_variables, dead_code)
+)]
+
 use std::collections::hash_map::DefaultHasher;
 use std::fs::{create_dir_all, File, Metadata};
 use std::hash::{Hash, Hasher};
@@ -5,6 +11,7 @@ use std::io::Write;
 use std::path::Path;
 
 use anyhow::Result;
+#[cfg(not(target_family = "wasm"))]
 use cacache::Error::EntryNotFound;
 use filetime::FileTime;
 use log::error;
@@ -107,6 +114,7 @@ pub fn get(
         return None;
     };
 
+    #[cfg(not(target_family = "wasm"))] // cacache needs async-std which doesn't support wasm
     match cacache::read_sync(cache_dir(), cache_key(path, settings, autofix)) {
         Ok(encoded) => match bincode::deserialize::<CheckResult>(&encoded[..]) {
             Ok(CheckResult {
@@ -137,12 +145,14 @@ pub fn set(
         return;
     };
 
+    #[cfg(not(target_family = "wasm"))] // modification date not supported on wasm
     let check_result = CheckResultRef {
         metadata: &CacheMetadata {
             mtime: FileTime::from_last_modification_time(metadata).unix_seconds(),
         },
         messages,
     };
+    #[cfg(not(target_family = "wasm"))] // cacache needs async-std which doesn't support wasm
     if let Err(e) = cacache::write_sync(
         cache_dir(),
         cache_key(path, settings, autofix),

src/check_lines.rs

@@ -1,10 +1,11 @@
 use std::collections::BTreeMap;
 
-use crate::ast::types::Range;
 use rustpython_parser::ast::Location;
 
+use crate::ast::types::Range;
 use crate::autofix::fixer;
-use crate::checks::{Check, CheckCode, CheckKind, Fix};
+use crate::autofix::Fix;
+use crate::checks::{Check, CheckCode, CheckKind};
 use crate::noqa;
 use crate::noqa::Directive;
 use crate::settings::Settings;
@@ -66,12 +67,12 @@ pub fn check_lines(
 
                 match noqa {
                     (Directive::All(_, _), matches) => {
-                        matches.push(check.kind.code().as_str());
+                        matches.push(check.kind.code().as_ref());
                         ignored.push(index)
                     }
                     (Directive::Codes(_, _, codes), matches) => {
-                        if codes.contains(&check.kind.code().as_str()) {
-                            matches.push(check.kind.code().as_str());
+                        if codes.contains(&check.kind.code().as_ref()) {
+                            matches.push(check.kind.code().as_ref());
                             ignored.push(index);
                         }
                     }
@@ -98,11 +99,11 @@ pub fn check_lines(
 
                 match noqa {
                     (Directive::All(_, _), matches) => {
-                        matches.push(check.kind.code().as_str());
+                        matches.push(check.kind.code().as_ref());
                     }
                     (Directive::Codes(_, _, codes), matches) => {
-                        if codes.contains(&check.kind.code().as_str()) {
-                            matches.push(check.kind.code().as_str());
+                        if codes.contains(&check.kind.code().as_ref()) {
+                            matches.push(check.kind.code().as_ref());
                         } else {
                             line_checks.push(check);
                         }
@@ -113,6 +114,45 @@ pub fn check_lines(
         }
     }
 
+    // Enforce newlines at end of files.
+    if settings.enabled.contains(&CheckCode::W292) && !contents.ends_with('\n') {
+        // Note: if `lines.last()` is `None`, then `contents` is empty (and so we don't want to
+        // raise W292 anyway).
+        if let Some(line) = lines.last() {
+            let lineno = lines.len() - 1;
+            let noqa_lineno = noqa_line_for
+                .get(lineno)
+                .map(|lineno| lineno - 1)
+                .unwrap_or(lineno);
+
+            let noqa = noqa_directives
+                .entry(noqa_lineno)
+                .or_insert_with(|| (noqa::extract_noqa_directive(lines[noqa_lineno]), vec![]));
+
+            let check = Check::new(
+                CheckKind::NoNewLineAtEndOfFile,
+                Range {
+                    location: Location::new(lines.len(), line.len() + 1),
+                    end_location: Location::new(lines.len(), line.len() + 1),
+                },
+            );
+
+            match noqa {
+                (Directive::All(_, _), matches) => {
+                    matches.push(check.kind.code().as_ref());
+                }
+                (Directive::Codes(_, _, codes), matches) => {
+                    if codes.contains(&check.kind.code().as_ref()) {
+                        matches.push(check.kind.code().as_ref());
+                    } else {
+                        line_checks.push(check);
+                    }
+                }
+                (Directive::None, _) => line_checks.push(check),
+            }
+        }
+    }
+
     // Enforce that the noqa directive was actually used.
     if enforce_noqa {
         for (row, (directive, matches)) in noqa_directives {
@@ -127,15 +167,10 @@ pub fn check_lines(
                             },
                         );
                         if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                            check.amend(Fix {
-                                content: "".to_string(),
-                                location: Location::new(row + 1, start + 1),
-                                end_location: Location::new(
-                                    row + 1,
-                                    lines[row].chars().count() + 1,
-                                ),
-                                applied: false,
-                            });
+                            check.amend(Fix::deletion(
+                                Location::new(row + 1, start + 1),
+                                Location::new(row + 1, lines[row].chars().count() + 1),
+                            ));
                         }
                         line_checks.push(check);
                     }
@@ -145,15 +180,15 @@ pub fn check_lines(
                     let mut valid_codes = vec![];
                     for code in codes {
                         if !matches.contains(&code) {
-                            invalid_codes.push(code);
+                            invalid_codes.push(code.to_string());
                         } else {
-                            valid_codes.push(code);
+                            valid_codes.push(code.to_string());
                         }
                     }
 
                     if !invalid_codes.is_empty() {
                         let mut check = Check::new(
-                            CheckKind::UnusedNOQA(Some(invalid_codes.join(", "))),
+                            CheckKind::UnusedNOQA(Some(invalid_codes)),
                             Range {
                                 location: Location::new(row + 1, start + 1),
                                 end_location: Location::new(row + 1, end + 1),
@@ -161,25 +196,16 @@ pub fn check_lines(
                         );
                         if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
                             if valid_codes.is_empty() {
-                                check.amend(Fix {
-                                    content: "".to_string(),
-                                    location: Location::new(row + 1, start + 1),
-                                    end_location: Location::new(
-                                        row + 1,
-                                        lines[row].chars().count() + 1,
-                                    ),
-                                    applied: false,
-                                });
+                                check.amend(Fix::deletion(
+                                    Location::new(row + 1, start + 1),
+                                    Location::new(row + 1, lines[row].chars().count() + 1),
+                                ));
                             } else {
-                                check.amend(Fix {
-                                    content: format!("  # noqa: {}", valid_codes.join(", ")),
-                                    location: Location::new(row + 1, start + 1),
-                                    end_location: Location::new(
-                                        row + 1,
-                                        lines[row].chars().count() + 1,
-                                    ),
-                                    applied: false,
-                                });
+                                check.amend(Fix::replacement(
+                                    format!("  # noqa: {}", valid_codes.join(", ")),
+                                    Location::new(row + 1, start + 1),
+                                    Location::new(row + 1, lines[row].chars().count() + 1),
+                                ));
                             }
                         }
                         line_checks.push(check);

src/cli.rs

@@ -17,6 +17,9 @@ use crate::RawSettings;
 pub struct Cli {
     #[arg(required = true)]
     pub files: Vec<PathBuf>,
+    /// Path to the `pyproject.toml` file to use for configuration.
+    #[arg(long)]
+    pub config: Option<PathBuf>,
     /// Enable verbose logging.
     #[arg(short, long)]
     pub verbose: bool,
@@ -78,6 +81,9 @@ pub struct Cli {
     // TODO(charlie): This should be a sub-command.
     #[arg(long, hide = true)]
     pub autoformat: bool,
+    /// The name of the file when passing it through stdin.
+    #[arg(long)]
+    pub stdin_filename: Option<String>,
 }
 
 pub enum Warnable {
@@ -97,9 +103,9 @@ impl fmt::Display for Warnable {
 /// Warn the user if they attempt to enable a code that won't be respected.
 pub fn warn_on(
     flag: Warnable,
-    codes: &Vec<CheckCode>,
-    cli_ignore: &Vec<CheckCode>,
-    cli_extend_ignore: &Vec<CheckCode>,
+    codes: &[CheckCode],
+    cli_ignore: &[CheckCode],
+    cli_extend_ignore: &[CheckCode],
     pyproject_settings: &RawSettings,
     pyproject_path: &Option<PathBuf>,
 ) {

src/code_gen.rs

@@ -115,7 +115,7 @@ impl SourceGenerator {
         Ok(())
     }
 
-    fn unparse_stmt<U>(&mut self, ast: &Stmt<U>) -> fmt::Result {
+    pub fn unparse_stmt<U>(&mut self, ast: &Stmt<U>) -> fmt::Result {
         macro_rules! statement {
             ($body:block) => {{
                 self.newline()?;
@@ -547,7 +547,7 @@ impl SourceGenerator {
         Ok(())
     }
 
-    fn unparse_expr<U>(&mut self, ast: &Expr<U>, level: u8) -> fmt::Result {
+    pub fn unparse_expr<U>(&mut self, ast: &Expr<U>, level: u8) -> fmt::Result {
         macro_rules! opprec {
             ($opty:ident, $x:expr, $enu:path, $($var:ident($op:literal, $prec:ident)),*$(,)?) => {
                 match $x {

src/docstrings/definition.rs

@@ -0,0 +1,23 @@
+use rustpython_ast::{Expr, Stmt};
+
+#[derive(Debug)]
+pub enum DefinitionKind<'a> {
+    Module,
+    Package,
+    Class(&'a Stmt),
+    NestedClass(&'a Stmt),
+    Function(&'a Stmt),
+    NestedFunction(&'a Stmt),
+    Method(&'a Stmt),
+}
+
+#[derive(Debug)]
+pub struct Definition<'a> {
+    pub kind: DefinitionKind<'a>,
+    pub docstring: Option<&'a Expr>,
+}
+
+pub enum Documentable {
+    Class,
+    Function,
+}

src/docstrings/extraction.rs

@@ -0,0 +1,82 @@
+//! Extract docstrings from an AST.
+
+use rustpython_ast::{Constant, Expr, ExprKind, Stmt, StmtKind};
+
+use crate::docstrings::definition::{Definition, DefinitionKind, Documentable};
+use crate::visibility::{Modifier, VisibleScope};
+
+/// Extract a docstring from a function or class body.
+pub fn docstring_from(suite: &[Stmt]) -> Option<&Expr> {
+    if let Some(stmt) = suite.first() {
+        if let StmtKind::Expr { value } = &stmt.node {
+            if matches!(
+                &value.node,
+                ExprKind::Constant {
+                    value: Constant::Str(_),
+                    ..
+                }
+            ) {
+                return Some(value);
+            }
+        }
+    }
+    None
+}
+
+/// Extract a `Definition` from the AST node defined by a `Stmt`.
+pub fn extract<'a>(
+    scope: &VisibleScope,
+    stmt: &'a Stmt,
+    body: &'a [Stmt],
+    kind: &Documentable,
+) -> Definition<'a> {
+    let expr = docstring_from(body);
+    match kind {
+        Documentable::Function => match scope {
+            VisibleScope {
+                modifier: Modifier::Module,
+                ..
+            } => Definition {
+                kind: DefinitionKind::Function(stmt),
+                docstring: expr,
+            },
+            VisibleScope {
+                modifier: Modifier::Class,
+                ..
+            } => Definition {
+                kind: DefinitionKind::Method(stmt),
+                docstring: expr,
+            },
+            VisibleScope {
+                modifier: Modifier::Function,
+                ..
+            } => Definition {
+                kind: DefinitionKind::NestedFunction(stmt),
+                docstring: expr,
+            },
+        },
+        Documentable::Class => match scope {
+            VisibleScope {
+                modifier: Modifier::Module,
+                ..
+            } => Definition {
+                kind: DefinitionKind::Class(stmt),
+                docstring: expr,
+            },
+            VisibleScope {
+                modifier: Modifier::Class,
+                ..
+            } => Definition {
+                kind: DefinitionKind::NestedClass(stmt),
+                docstring: expr,
+            },
+            VisibleScope {
+                modifier: Modifier::Function,
+                ..
+            } => Definition {
+                kind: DefinitionKind::NestedClass(stmt),
+                docstring: expr,
+            },
+        },
+    }
+}

src/docstrings/google.rs

@@ -0,0 +1,71 @@
+//! Abstractions for Google-style docstrings.
+
+use std::collections::BTreeSet;
+
+use once_cell::sync::Lazy;
+
+pub(crate) static GOOGLE_SECTION_NAMES: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
+    BTreeSet::from([
+        "Args",
+        "Arguments",
+        "Attention",
+        "Attributes",
+        "Caution",
+        "Danger",
+        "Error",
+        "Example",
+        "Examples",
+        "Hint",
+        "Important",
+        "Keyword Args",
+        "Keyword Arguments",
+        "Methods",
+        "Note",
+        "Notes",
+        "Return",
+        "Returns",
+        "Raises",
+        "References",
+        "See Also",
+        "Tip",
+        "Todo",
+        "Warning",
+        "Warnings",
+        "Warns",
+        "Yield",
+        "Yields",
+    ])
+});
+
+pub(crate) static LOWERCASE_GOOGLE_SECTION_NAMES: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
+    BTreeSet::from([
+        "args",
+        "arguments",
+        "attention",
+        "attributes",
+        "caution",
+        "danger",
+        "error",
+        "example",
+        "examples",
+        "hint",
+        "important",
+        "keyword args",
+        "keyword arguments",
+        "methods",
+        "note",
+        "notes",
+        "return",
+        "returns",
+        "raises",
+        "references",
+        "see also",
+        "tip",
+        "todo",
+        "warning",
+        "warnings",
+        "warns",
+        "yield",
+        "yields",
+    ])
+});

src/docstrings/helpers.rs

@@ -0,0 +1,42 @@
+use rustpython_ast::{Expr, Location};
+
+use crate::ast::types::Range;
+use crate::check_ast::Checker;
+
+pub const TRIPLE_QUOTE_PREFIXES: &[&str] = &[
+    "ur\"\"\"", "ur'''", "u\"\"\"", "u'''", "r\"\"\"", "r'''", "\"\"\"", "'''",
+];
+
+pub const SINGLE_QUOTE_PREFIXES: &[&str] = &["ur\"", "ur'", "u\"", "u'", "r\"", "r'", "\"", "'"];
+
+/// Extract the leading words from a line of text.
+pub fn leading_words(line: &str) -> String {
+    line.trim()
+        .chars()
+        .take_while(|char| char.is_alphanumeric() || char.is_whitespace())
+        .collect()
+}
+
+/// Extract the leading whitespace from a line of text.
+pub fn leading_space(line: &str) -> String {
+    line.chars()
+        .take_while(|char| char.is_whitespace())
+        .collect()
+}
+
+/// Extract the leading indentation from a docstring.
+pub fn indentation<'a>(checker: &'a mut Checker, docstring: &Expr) -> &'a str {
+    let range = Range::from_located(docstring);
+    checker.locator.slice_source_code_range(&Range {
+        location: Location::new(range.location.row(), 1),
+        end_location: Location::new(range.location.row(), range.location.column()),
+    })
+}
+
+/// Replace any non-whitespace characters from an indentation string.
+pub fn clean(indentation: &str) -> String {
+    indentation
+        .chars()
+        .map(|char| if char.is_whitespace() { char } else { ' ' })
+        .collect()
+}

src/docstrings/mod.rs

@@ -0,0 +1,7 @@
+pub mod definition;
+pub mod extraction;
+pub mod google;
+pub mod helpers;
+pub mod numpy;
+pub mod sections;
+pub mod styles;

src/docstrings/numpy.rs

@@ -0,0 +1,41 @@
+//! Abstractions for NumPy-style docstrings.
+
+use std::collections::BTreeSet;
+
+use once_cell::sync::Lazy;
+
+pub(crate) static LOWERCASE_NUMPY_SECTION_NAMES: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
+    BTreeSet::from([
+        "short summary",
+        "extended summary",
+        "parameters",
+        "returns",
+        "yields",
+        "other parameters",
+        "raises",
+        "see also",
+        "notes",
+        "references",
+        "examples",
+        "attributes",
+        "methods",
+    ])
+});
+
+pub(crate) static NUMPY_SECTION_NAMES: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
+    BTreeSet::from([
+        "Short Summary",
+        "Extended Summary",
+        "Parameters",
+        "Returns",
+        "Yields",
+        "Other Parameters",
+        "Raises",
+        "See Also",
+        "Notes",
+        "References",
+        "Examples",
+        "Attributes",
+        "Methods",
+    ])
+});

src/docstrings/sections.rs

@@ -0,0 +1,99 @@
+use crate::docstrings::helpers;
+use crate::docstrings::styles::SectionStyle;
+
+#[derive(Debug)]
+pub(crate) struct SectionContext<'a> {
+    pub(crate) section_name: String,
+    pub(crate) previous_line: &'a str,
+    pub(crate) line: &'a str,
+    pub(crate) following_lines: &'a [&'a str],
+    pub(crate) is_last_section: bool,
+    pub(crate) original_index: usize,
+}
+
+fn suspected_as_section(line: &str, style: &SectionStyle) -> bool {
+    style
+        .lowercase_section_names()
+        .contains(&helpers::leading_words(line).to_lowercase().as_str())
+}
+
+/// Check if the suspected context is really a section header.
+fn is_docstring_section(context: &SectionContext) -> bool {
+    let section_name_suffix = context
+        .line
+        .trim()
+        .strip_prefix(&context.section_name)
+        .unwrap()
+        .trim();
+    let this_looks_like_a_section_name =
+        section_name_suffix == ":" || section_name_suffix.is_empty();
+    if !this_looks_like_a_section_name {
+        return false;
+    }
+
+    let prev_line = context.previous_line.trim();
+    let prev_line_ends_with_punctuation = [',', ';', '.', '-', '\\', '/', ']', '}', ')']
+        .into_iter()
+        .any(|char| prev_line.ends_with(char));
+    let prev_line_looks_like_end_of_paragraph =
+        prev_line_ends_with_punctuation || prev_line.is_empty();
+    if !prev_line_looks_like_end_of_paragraph {
+        return false;
+    }
+
+    true
+}
+
+/// Extract all `SectionContext` values from a docstring.
+pub(crate) fn section_contexts<'a>(
+    lines: &'a [&'a str],
+    style: &SectionStyle,
+) -> Vec<SectionContext<'a>> {
+    let suspected_section_indices: Vec<usize> = lines
+        .iter()
+        .enumerate()
+        .filter_map(|(lineno, line)| {
+            if lineno > 0 && suspected_as_section(line, style) {
+                Some(lineno)
+            } else {
+                None
+            }
+        })
+        .collect();
+
+    let mut contexts = vec![];
+    for lineno in suspected_section_indices {
+        let context = SectionContext {
+            section_name: helpers::leading_words(lines[lineno]),
+            previous_line: lines[lineno - 1],
+            line: lines[lineno],
+            following_lines: &lines[lineno + 1..],
+            original_index: lineno,
+            is_last_section: false,
+        };
+        if is_docstring_section(&context) {
+            contexts.push(context);
+        }
+    }
+
+    let mut truncated_contexts = vec![];
+    let mut end: Option<usize> = None;
+    for context in contexts.into_iter().rev() {
+        let next_end = context.original_index;
+        truncated_contexts.push(SectionContext {
+            section_name: context.section_name,
+            previous_line: context.previous_line,
+            line: context.line,
+            following_lines: if let Some(end) = end {
+                &lines[context.original_index + 1..end]
+            } else {
+                context.following_lines
+            },
+            original_index: context.original_index,
+            is_last_section: end.is_none(),
+        });
+        end = Some(next_end);
+    }
+    truncated_contexts.reverse();
+    truncated_contexts
+}

src/docstrings/styles.rs

@@ -0,0 +1,27 @@
+use std::collections::BTreeSet;
+
+use once_cell::sync::Lazy;
+
+use crate::docstrings::google::{GOOGLE_SECTION_NAMES, LOWERCASE_GOOGLE_SECTION_NAMES};
+use crate::docstrings::numpy::{LOWERCASE_NUMPY_SECTION_NAMES, NUMPY_SECTION_NAMES};
+
+pub(crate) enum SectionStyle {
+    NumPy,
+    Google,
+}
+
+impl SectionStyle {
+    pub(crate) fn section_names(&self) -> &Lazy<BTreeSet<&'static str>> {
+        match self {
+            SectionStyle::NumPy => &NUMPY_SECTION_NAMES,
+            SectionStyle::Google => &GOOGLE_SECTION_NAMES,
+        }
+    }
+
+    pub(crate) fn lowercase_section_names(&self) -> &Lazy<BTreeSet<&'static str>> {
+        match self {
+            SectionStyle::NumPy => &LOWERCASE_NUMPY_SECTION_NAMES,
+            SectionStyle::Google => &LOWERCASE_GOOGLE_SECTION_NAMES,
+        }
+    }
+}

src/flake8_bugbear/mod.rs

@@ -0,0 +1 @@
+pub mod plugins;

src/flake8_bugbear/plugins/assert_false.rs

@@ -0,0 +1,61 @@
+use rustpython_ast::{Constant, Expr, ExprContext, ExprKind, Stmt, StmtKind};
+
+use crate::ast::types::Range;
+use crate::autofix::fixer;
+use crate::autofix::Fix;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckKind};
+use crate::code_gen::SourceGenerator;
+
+fn assertion_error(msg: &Option<Box<Expr>>) -> Stmt {
+    Stmt::new(
+        Default::default(),
+        Default::default(),
+        StmtKind::Raise {
+            exc: Some(Box::new(Expr::new(
+                Default::default(),
+                Default::default(),
+                ExprKind::Call {
+                    func: Box::new(Expr::new(
+                        Default::default(),
+                        Default::default(),
+                        ExprKind::Name {
+                            id: "AssertionError".to_string(),
+                            ctx: ExprContext::Load,
+                        },
+                    )),
+                    args: if let Some(msg) = msg {
+                        vec![*msg.clone()]
+                    } else {
+                        vec![]
+                    },
+                    keywords: vec![],
+                },
+            ))),
+            cause: None,
+        },
+    )
+}
+
+pub fn assert_false(checker: &mut Checker, stmt: &Stmt, test: &Expr, msg: &Option<Box<Expr>>) {
+    if let ExprKind::Constant {
+        value: Constant::Bool(false),
+        ..
+    } = &test.node
+    {
+        let mut check = Check::new(CheckKind::DoNotAssertFalse, Range::from_located(test));
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            let mut generator = SourceGenerator::new();
+            if let Ok(()) = generator.unparse_stmt(&assertion_error(msg)) {
+                if let Ok(content) = generator.generate() {
+                    check.amend(Fix::replacement(
+                        content,
+                        stmt.location,
+                        stmt.end_location.unwrap(),
+                    ));
+                }
+            }
+        }
+        checker.add_check(check);
+    }
+}

src/flake8_bugbear/plugins/duplicate_exceptions.rs

@@ -0,0 +1,114 @@
+use std::collections::BTreeSet;
+
+use itertools::Itertools;
+use rustpython_ast::{Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind, Stmt};
+
+use crate::ast::helpers;
+use crate::ast::types::{CheckLocator, Range};
+use crate::autofix::fixer;
+use crate::autofix::Fix;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckCode, CheckKind};
+use crate::code_gen::SourceGenerator;
+
+fn type_pattern(elts: Vec<&Expr>) -> Expr {
+    Expr::new(
+        Default::default(),
+        Default::default(),
+        ExprKind::Tuple {
+            elts: elts.into_iter().cloned().collect(),
+            ctx: ExprContext::Load,
+        },
+    )
+}
+
+pub fn duplicate_handler_exceptions(
+    checker: &mut Checker,
+    expr: &Expr,
+    elts: &[Expr],
+) -> BTreeSet<String> {
+    let mut seen: BTreeSet<String> = Default::default();
+    let mut duplicates: BTreeSet<String> = Default::default();
+    let mut unique_elts: Vec<&Expr> = Default::default();
+    for type_ in elts {
+        if let Some(name) = helpers::compose_call_path(type_) {
+            if seen.contains(&name) {
+                duplicates.insert(name);
+            } else {
+                seen.insert(name);
+                unique_elts.push(type_);
+            }
+        }
+    }
+
+    if checker.settings.enabled.contains(&CheckCode::B014) {
+        // TODO(charlie): Handle "BaseException" and redundant exception aliases.
+        if !duplicates.is_empty() {
+            let mut check = Check::new(
+                CheckKind::DuplicateHandlerException(
+                    duplicates.into_iter().sorted().collect::<Vec<String>>(),
+                ),
+                checker.locate_check(Range::from_located(expr)),
+            );
+            if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+                // TODO(charlie): If we have a single element, remove the tuple.
+                let mut generator = SourceGenerator::new();
+                if let Ok(()) = generator.unparse_expr(&type_pattern(unique_elts), 0) {
+                    if let Ok(content) = generator.generate() {
+                        check.amend(Fix::replacement(
+                            content,
+                            expr.location,
+                            expr.end_location.unwrap(),
+                        ))
+                    }
+                }
+            }
+            checker.add_check(check);
+        }
+    }
+
+    seen
+}
+
+pub fn duplicate_exceptions(checker: &mut Checker, stmt: &Stmt, handlers: &[Excepthandler]) {
+    let mut seen: BTreeSet<String> = Default::default();
+    let mut duplicates: BTreeSet<String> = Default::default();
+    for handler in handlers {
+        match &handler.node {
+            ExcepthandlerKind::ExceptHandler { type_, .. } => {
+                if let Some(type_) = type_ {
+                    match &type_.node {
+                        ExprKind::Attribute { .. } | ExprKind::Name { .. } => {
+                            if let Some(name) = helpers::compose_call_path(type_) {
+                                if seen.contains(&name) {
+                                    duplicates.insert(name);
+                                } else {
+                                    seen.insert(name);
+                                }
+                            }
+                        }
+                        ExprKind::Tuple { elts, .. } => {
+                            for name in duplicate_handler_exceptions(checker, type_, elts) {
+                                if seen.contains(&name) {
+                                    duplicates.insert(name);
+                                } else {
+                                    seen.insert(name);
+                                }
+                            }
+                        }
+                        _ => {}
+                    }
+                }
+            }
+        }
+    }
+
+    if checker.settings.enabled.contains(&CheckCode::B025) {
+        for duplicate in duplicates.into_iter().sorted() {
+            checker.add_check(Check::new(
+                CheckKind::DuplicateTryBlockException(duplicate),
+                checker.locate_check(Range::from_located(stmt)),
+            ));
+        }
+    }
+}

src/flake8_bugbear/plugins/mod.rs

@@ -0,0 +1,6 @@
+pub use assert_false::assert_false;
+pub use duplicate_exceptions::duplicate_exceptions;
+pub use duplicate_exceptions::duplicate_handler_exceptions;
+
+mod assert_false;
+mod duplicate_exceptions;

src/flake8_builtins/checks.rs

@@ -0,0 +1,20 @@
+use crate::ast::types::Range;
+use crate::checks::{Check, CheckKind};
+use crate::flake8_builtins::types::ShadowingType;
+use crate::python::builtins::BUILTINS;
+
+/// Check builtin name shadowing.
+pub fn builtin_shadowing(name: &str, location: Range, node_type: ShadowingType) -> Option<Check> {
+    if BUILTINS.contains(&name) {
+        Some(Check::new(
+            match node_type {
+                ShadowingType::Variable => CheckKind::BuiltinVariableShadowing(name.to_string()),
+                ShadowingType::Argument => CheckKind::BuiltinArgumentShadowing(name.to_string()),
+                ShadowingType::Attribute => CheckKind::BuiltinAttributeShadowing(name.to_string()),
+            },
+            location,
+        ))
+    } else {
+        None
+    }
+}

src/flake8_builtins/mod.rs

@@ -0,0 +1,2 @@
+pub mod checks;
+pub mod types;

src/flake8_builtins/types.rs

@@ -0,0 +1,5 @@
+pub enum ShadowingType {
+    Variable,
+    Argument,
+    Attribute,
+}

src/flake8_comprehensions/checks.rs

@@ -0,0 +1,505 @@
+use num_bigint::BigInt;
+use rustpython_ast::{Comprehension, Constant, Expr, ExprKind, KeywordData, Located, Unaryop};
+
+use crate::ast::types::Range;
+use crate::checks::{Check, CheckKind};
+
+/// Check `list(generator)` compliance.
+pub fn unnecessary_generator_list(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "list" {
+                if let ExprKind::GeneratorExp { .. } = &args[0].node {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryGeneratorList,
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `set(generator)` compliance.
+pub fn unnecessary_generator_set(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "set" {
+                if let ExprKind::GeneratorExp { .. } = &args[0].node {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryGeneratorSet,
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `dict((x, y) for x, y in iterable)` compliance.
+pub fn unnecessary_generator_dict(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "dict" {
+                if let ExprKind::GeneratorExp { elt, .. } = &args[0].node {
+                    match &elt.node {
+                        ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryGeneratorDict,
+                                Range::from_located(expr),
+                            ));
+                        }
+                        _ => {}
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `set([...])` compliance.
+pub fn unnecessary_list_comprehension_set(
+    expr: &Expr,
+    func: &Expr,
+    args: &[Expr],
+) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "set" {
+                if let ExprKind::ListComp { .. } = &args[0].node {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryListComprehensionSet,
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `dict([...])` compliance.
+pub fn unnecessary_list_comprehension_dict(
+    expr: &Expr,
+    func: &Expr,
+    args: &[Expr],
+) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "dict" {
+                if let ExprKind::ListComp { elt, .. } = &args[0].node {
+                    match &elt.node {
+                        ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryListComprehensionDict,
+                                Range::from_located(expr),
+                            ));
+                        }
+                        _ => {}
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `set([1, 2])` compliance.
+pub fn unnecessary_literal_set(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "set" {
+                match &args[0].node {
+                    ExprKind::List { .. } => {
+                        return Some(Check::new(
+                            CheckKind::UnnecessaryLiteralSet("list".to_string()),
+                            Range::from_located(expr),
+                        ));
+                    }
+                    ExprKind::Tuple { .. } => {
+                        return Some(Check::new(
+                            CheckKind::UnnecessaryLiteralSet("tuple".to_string()),
+                            Range::from_located(expr),
+                        ));
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `dict([(1, 2)])` compliance.
+pub fn unnecessary_literal_dict(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "dict" {
+                match &args[0].node {
+                    ExprKind::Tuple { elts, .. } => {
+                        if let Some(elt) = elts.first() {
+                            match &elt.node {
+                                // dict((1, 2), ...))
+                                ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
+                                    return Some(Check::new(
+                                        CheckKind::UnnecessaryLiteralDict("tuple".to_string()),
+                                        Range::from_located(expr),
+                                    ));
+                                }
+                                _ => {}
+                            }
+                        } else {
+                            // dict(())
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryLiteralDict("tuple".to_string()),
+                                Range::from_located(expr),
+                            ));
+                        }
+                    }
+                    ExprKind::List { elts, .. } => {
+                        if let Some(elt) = elts.first() {
+                            match &elt.node {
+                                // dict([(1, 2), ...])
+                                ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
+                                    return Some(Check::new(
+                                        CheckKind::UnnecessaryLiteralDict("list".to_string()),
+                                        Range::from_located(expr),
+                                    ));
+                                }
+                                _ => {}
+                            }
+                        } else {
+                            // dict([])
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryLiteralDict("list".to_string()),
+                                Range::from_located(expr),
+                            ));
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+    None
+}
+
+pub fn unnecessary_collection_call(
+    expr: &Expr,
+    func: &Expr,
+    args: &[Expr],
+    keywords: &[Located<KeywordData>],
+) -> Option<Check> {
+    if args.is_empty() {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "list" || id == "tuple" {
+                // list() or tuple()
+                return Some(Check::new(
+                    CheckKind::UnnecessaryCollectionCall(id.to_string()),
+                    Range::from_located(expr),
+                ));
+            } else if id == "dict" {
+                // dict() or dict(a=1)
+                if keywords.is_empty() || keywords.iter().all(|kw| kw.node.arg.is_some()) {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryCollectionCall(id.to_string()),
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        }
+    }
+    None
+}
+
+pub fn unnecessary_literal_within_tuple_call(
+    expr: &Expr,
+    func: &Expr,
+    args: &[Expr],
+) -> Option<Check> {
+    if let ExprKind::Name { id, .. } = &func.node {
+        if id == "tuple" {
+            if let Some(arg) = args.first() {
+                match &arg.node {
+                    ExprKind::Tuple { .. } => {
+                        return Some(Check::new(
+                            CheckKind::UnnecessaryLiteralWithinTupleCall("tuple".to_string()),
+                            Range::from_located(expr),
+                        ));
+                    }
+                    ExprKind::List { .. } => {
+                        return Some(Check::new(
+                            CheckKind::UnnecessaryLiteralWithinTupleCall("list".to_string()),
+                            Range::from_located(expr),
+                        ));
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+
+    None
+}
+
+pub fn unnecessary_literal_within_list_call(
+    expr: &Expr,
+    func: &Expr,
+    args: &[Expr],
+) -> Option<Check> {
+    if let ExprKind::Name { id, .. } = &func.node {
+        if id == "list" {
+            if let Some(arg) = args.first() {
+                match &arg.node {
+                    ExprKind::Tuple { .. } => {
+                        return Some(Check::new(
+                            CheckKind::UnnecessaryLiteralWithinListCall("tuple".to_string()),
+                            Range::from_located(expr),
+                        ));
+                    }
+                    ExprKind::List { .. } => {
+                        return Some(Check::new(
+                            CheckKind::UnnecessaryLiteralWithinListCall("list".to_string()),
+                            Range::from_located(expr),
+                        ));
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+
+    None
+}
+
+pub fn unnecessary_list_call(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if let ExprKind::Name { id, .. } = &func.node {
+        if id == "list" {
+            if let Some(arg) = args.first() {
+                if let ExprKind::ListComp { .. } = &arg.node {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryListCall,
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        }
+    }
+    None
+}
+
+pub fn unnecessary_call_around_sorted(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if let ExprKind::Name { id: outer, .. } = &func.node {
+        if outer == "list" || outer == "reversed" {
+            if let Some(arg) = args.first() {
+                if let ExprKind::Call { func, .. } = &arg.node {
+                    if let ExprKind::Name { id: inner, .. } = &func.node {
+                        if inner == "sorted" {
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryCallAroundSorted(outer.to_string()),
+                                Range::from_located(expr),
+                            ));
+                        }
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
+pub fn unnecessary_double_cast_or_process(
+    expr: &Expr,
+    func: &Expr,
+    args: &[Expr],
+) -> Option<Check> {
+    if let ExprKind::Name { id: outer, .. } = &func.node {
+        if outer == "list"
+            || outer == "tuple"
+            || outer == "set"
+            || outer == "reversed"
+            || outer == "sorted"
+        {
+            if let Some(arg) = args.first() {
+                if let ExprKind::Call { func, .. } = &arg.node {
+                    if let ExprKind::Name { id: inner, .. } = &func.node {
+                        // Ex) set(tuple(...))
+                        if (outer == "set" || outer == "sorted")
+                            && (inner == "list"
+                                || inner == "tuple"
+                                || inner == "reversed"
+                                || inner == "sorted")
+                        {
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryDoubleCastOrProcess(
+                                    inner.to_string(),
+                                    outer.to_string(),
+                                ),
+                                Range::from_located(expr),
+                            ));
+                        }
+
+                        // Ex) list(tuple(...))
+                        if (outer == "list" || outer == "tuple")
+                            && (inner == "list" || inner == "tuple")
+                        {
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryDoubleCastOrProcess(
+                                    inner.to_string(),
+                                    outer.to_string(),
+                                ),
+                                Range::from_located(expr),
+                            ));
+                        }
+
+                        // Ex) set(set(...))
+                        if outer == "set" && inner == "set" {
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryDoubleCastOrProcess(
+                                    inner.to_string(),
+                                    outer.to_string(),
+                                ),
+                                Range::from_located(expr),
+                            ));
+                        }
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
+pub fn unnecessary_subscript_reversal(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if let Some(first_arg) = args.first() {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "set" || id == "sorted" || id == "reversed" {
+                if let ExprKind::Subscript { slice, .. } = &first_arg.node {
+                    if let ExprKind::Slice { lower, upper, step } = &slice.node {
+                        if lower.is_none() && upper.is_none() {
+                            if let Some(step) = step {
+                                if let ExprKind::UnaryOp {
+                                    op: Unaryop::USub,
+                                    operand,
+                                } = &step.node
+                                {
+                                    if let ExprKind::Constant {
+                                        value: Constant::Int(val),
+                                        ..
+                                    } = &operand.node
+                                    {
+                                        if *val == BigInt::from(1) {
+                                            return Some(Check::new(
+                                                CheckKind::UnnecessarySubscriptReversal(
+                                                    id.to_string(),
+                                                ),
+                                                Range::from_located(expr),
+                                            ));
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
+pub fn unnecessary_comprehension(
+    expr: &Expr,
+    elt: &Expr,
+    generators: &[Comprehension],
+) -> Option<Check> {
+    if generators.len() == 1 {
+        let generator = &generators[0];
+        if generator.ifs.is_empty() && generator.is_async == 0 {
+            if let ExprKind::Name { id: elt_id, .. } = &elt.node {
+                if let ExprKind::Name { id: target_id, .. } = &generator.target.node {
+                    if elt_id == target_id {
+                        match &expr.node {
+                            ExprKind::ListComp { .. } => {
+                                return Some(Check::new(
+                                    CheckKind::UnnecessaryComprehension("list".to_string()),
+                                    Range::from_located(expr),
+                                ))
+                            }
+                            ExprKind::SetComp { .. } => {
+                                return Some(Check::new(
+                                    CheckKind::UnnecessaryComprehension("set".to_string()),
+                                    Range::from_located(expr),
+                                ))
+                            }
+                            _ => {}
+                        };
+                    }
+                }
+            }
+        }
+    }
+
+    None
+}
+
+pub fn unnecessary_map(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if let ExprKind::Name { id, .. } = &func.node {
+        if id == "map" {
+            if args.len() == 2 {
+                if let ExprKind::Lambda { .. } = &args[0].node {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryMap("generator".to_string()),
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        } else if id == "list" || id == "set" {
+            if let Some(arg) = args.first() {
+                if let ExprKind::Call { func, args, .. } = &arg.node {
+                    if let ExprKind::Name { id: f, .. } = &func.node {
+                        if f == "map" {
+                            if let Some(arg) = args.first() {
+                                if let ExprKind::Lambda { .. } = &arg.node {
+                                    return Some(Check::new(
+                                        CheckKind::UnnecessaryMap(id.to_string()),
+                                        Range::from_located(expr),
+                                    ));
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        } else if id == "dict" {
+            if args.len() == 1 {
+                if let ExprKind::Call { func, args, .. } = &args[0].node {
+                    if let ExprKind::Name { id: f, .. } = &func.node {
+                        if f == "map" {
+                            if let Some(arg) = args.first() {
+                                if let ExprKind::Lambda { body, .. } = &arg.node {
+                                    match &body.node {
+                                        ExprKind::Tuple { elts, .. }
+                                        | ExprKind::List { elts, .. }
+                                            if elts.len() == 2 =>
+                                        {
+                                            return Some(Check::new(
+                                                CheckKind::UnnecessaryMap(id.to_string()),
+                                                Range::from_located(expr),
+                                            ))
+                                        }
+                                        _ => {}
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+    None
+}

src/flake8_comprehensions/mod.rs

@@ -0,0 +1 @@
+pub mod checks;

src/flake8_print/checks.rs

@@ -0,0 +1,36 @@
+use rustpython_ast::{Expr, ExprKind};
+
+use crate::ast::types::Range;
+use crate::checks::{Check, CheckKind};
+
+/// Check whether a function call is a `print` or `pprint` invocation
+pub fn print_call(
+    expr: &Expr,
+    func: &Expr,
+    check_print: bool,
+    check_pprint: bool,
+) -> Option<Check> {
+    if let ExprKind::Name { id, .. } = &func.node {
+        if check_print && id == "print" {
+            return Some(Check::new(CheckKind::PrintFound, Range::from_located(expr)));
+        } else if check_pprint && id == "pprint" {
+            return Some(Check::new(
+                CheckKind::PPrintFound,
+                Range::from_located(expr),
+            ));
+        }
+    }
+
+    if let ExprKind::Attribute { value, attr, .. } = &func.node {
+        if let ExprKind::Name { id, .. } = &value.node {
+            if check_pprint && id == "pprint" && attr == "pprint" {
+                return Some(Check::new(
+                    CheckKind::PPrintFound,
+                    Range::from_located(expr),
+                ));
+            }
+        }
+    }
+
+    None
+}

src/flake8_print/mod.rs

@@ -0,0 +1,2 @@
+mod checks;
+pub mod plugins;

src/flake8_print/plugins/mod.rs

@@ -0,0 +1,3 @@
+pub use print_call::print_call;
+
+mod print_call;

src/flake8_print/plugins/print_call.rs

@@ -1,13 +1,13 @@
 use log::error;
 use rustpython_ast::{Expr, Stmt, StmtKind};
 
-use crate::ast::checks;
-use crate::autofix::{fixer, fixes};
+use crate::autofix::{fixer, helpers};
 use crate::check_ast::Checker;
 use crate::checks::CheckCode;
+use crate::flake8_print::checks;
 
 pub fn print_call(checker: &mut Checker, expr: &Expr, func: &Expr) {
-    if let Some(mut check) = checks::check_print_call(
+    if let Some(mut check) = checks::print_call(
         expr,
         func,
         checker.settings.enabled.contains(&CheckCode::T201),
@@ -25,13 +25,13 @@ pub fn print_call(checker: &mut Checker, expr: &Expr, func: &Expr) {
                     .map(|index| checker.parents[*index])
                     .collect();
 
-                match fixes::remove_stmt(
+                match helpers::remove_stmt(
                     checker.parents[context.defined_by],
                     context.defined_in.map(|index| checker.parents[index]),
                     &deleted,
                 ) {
                     Ok(fix) => {
-                        if fix.content.is_empty() || fix.content == "pass" {
+                        if fix.patch.content.is_empty() || fix.patch.content == "pass" {
                             checker.deletions.insert(context.defined_by);
                         }
                         check.amend(fix)

src/lib.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::collapsible_if, clippy::collapsible_else_if)]
+
 use std::path::Path;
 
 use anyhow::Result;
@@ -17,16 +19,26 @@ mod check_lines;
 pub mod checks;
 pub mod cli;
 pub mod code_gen;
+mod docstrings;
+mod flake8_bugbear;
+mod flake8_builtins;
+mod flake8_comprehensions;
+mod flake8_print;
 pub mod fs;
 pub mod linter;
 pub mod logging;
 pub mod message;
 mod noqa;
-mod plugins;
+mod pep8_naming;
 pub mod printer;
+mod pycodestyle;
+mod pydocstyle;
+mod pyflakes;
 pub mod pyproject;
 mod python;
+mod pyupgrade;
 pub mod settings;
+pub mod visibility;
 
 /// Run ruff over Python source code directly.
 pub fn check(path: &Path, contents: &str) -> Result<Vec<Message>> {

src/linter.rs

@@ -1,7 +1,10 @@
 use std::fs::write;
+use std::io;
+use std::io::Write;
 use std::path::Path;
 
 use anyhow::Result;
+#[cfg(not(target_family = "wasm"))]
 use log::debug;
 use rustpython_parser::lexer::LexResult;
 use rustpython_parser::{lexer, parser};
@@ -75,7 +78,7 @@ pub(crate) fn check_path(
         if !ignores.is_empty() {
             return Ok(checks
                 .into_iter()
-                .filter(|check| !ignores.contains(check.kind.code()))
+                .filter(|check| !ignores.contains(&check.kind.code()))
                 .collect());
         }
     }
@@ -83,6 +86,44 @@ pub(crate) fn check_path(
     Ok(checks)
 }
 
+pub fn lint_stdin(
+    path: &Path,
+    stdin: &str,
+    settings: &Settings,
+    autofix: &fixer::Mode,
+) -> Result<Vec<Message>> {
+    // Tokenize once.
+    let tokens: Vec<LexResult> = tokenize(stdin);
+
+    // Determine the noqa line for every line in the source.
+    let noqa_line_for = noqa::extract_noqa_line_for(&tokens);
+
+    // Generate checks.
+    let mut checks = check_path(path, stdin, tokens, &noqa_line_for, settings, autofix)?;
+
+    // Apply autofix, write results to stdout.
+    if matches!(autofix, fixer::Mode::Apply) {
+        let output = match fix_file(&mut checks, stdin) {
+            None => stdin.to_string(),
+            Some(content) => content,
+        };
+        io::stdout().write_all(output.as_bytes())?;
+    }
+
+    // Convert to messages.
+    Ok(checks
+        .into_iter()
+        .map(|check| Message {
+            kind: check.kind,
+            fixed: check.fix.map(|fix| fix.applied).unwrap_or_default(),
+            location: check.location,
+            end_location: check.end_location,
+            filename: path.to_string_lossy().to_string(),
+        })
+        .collect())
+}
+
+#[cfg_attr(target_family = "wasm", allow(unused_variables))]
 pub fn lint_path(
     path: &Path,
     settings: &Settings,
@@ -92,6 +133,7 @@ pub fn lint_path(
     let metadata = path.metadata()?;
 
     // Check the cache.
+    #[cfg(not(target_family = "wasm"))]
     if let Some(messages) = cache::get(path, &metadata, settings, autofix, mode) {
         debug!("Cache hit for: {}", path.to_string_lossy());
         return Ok(messages);
@@ -111,7 +153,9 @@ pub fn lint_path(
 
     // Apply autofix.
     if matches!(autofix, fixer::Mode::Apply) {
-        fix_file(&mut checks, &contents, path)?;
+        if let Some(fixed_contents) = fix_file(&mut checks, &contents) {
+            write(path, fixed_contents)?;
+        }
     };
 
     // Convert to messages.
@@ -125,6 +169,7 @@ pub fn lint_path(
             filename: path.to_string_lossy().to_string(),
         })
         .collect();
+    #[cfg(not(target_family = "wasm"))]
     cache::set(path, &metadata, settings, autofix, &messages, mode);
 
     Ok(messages)
@@ -171,11 +216,13 @@ pub fn autoformat_path(path: &Path) -> Result<()> {
 
 #[cfg(test)]
 mod tests {
+    use std::convert::AsRef;
     use std::path::Path;
 
     use anyhow::Result;
     use regex::Regex;
     use rustpython_parser::lexer::LexResult;
+    use test_case::test_case;
 
     use crate::autofix::fixer;
     use crate::checks::{Check, CheckCode};
@@ -195,459 +242,144 @@ mod tests {
         linter::check_path(path, &contents, tokens, &noqa_line_for, settings, autofix)
     }
 
-    #[test]
-    fn e402() -> Result<()> {
+    #[test_case(CheckCode::A001, Path::new("A001.py"); "A001")]
+    #[test_case(CheckCode::A002, Path::new("A002.py"); "A002")]
+    #[test_case(CheckCode::A003, Path::new("A003.py"); "A003")]
+    #[test_case(CheckCode::B011, Path::new("B011.py"); "B011")]
+    #[test_case(CheckCode::B014, Path::new("B014.py"); "B014")]
+    #[test_case(CheckCode::B025, Path::new("B025.py"); "B025")]
+    #[test_case(CheckCode::C400, Path::new("C400.py"); "C400")]
+    #[test_case(CheckCode::C401, Path::new("C401.py"); "C401")]
+    #[test_case(CheckCode::C402, Path::new("C402.py"); "C402")]
+    #[test_case(CheckCode::C403, Path::new("C403.py"); "C403")]
+    #[test_case(CheckCode::C404, Path::new("C404.py"); "C404")]
+    #[test_case(CheckCode::C405, Path::new("C405.py"); "C405")]
+    #[test_case(CheckCode::C406, Path::new("C406.py"); "C406")]
+    #[test_case(CheckCode::C408, Path::new("C408.py"); "C408")]
+    #[test_case(CheckCode::C409, Path::new("C409.py"); "C409")]
+    #[test_case(CheckCode::C410, Path::new("C410.py"); "C410")]
+    #[test_case(CheckCode::C411, Path::new("C411.py"); "C411")]
+    #[test_case(CheckCode::C413, Path::new("C413.py"); "C413")]
+    #[test_case(CheckCode::C414, Path::new("C414.py"); "C414")]
+    #[test_case(CheckCode::C415, Path::new("C415.py"); "C415")]
+    #[test_case(CheckCode::C416, Path::new("C416.py"); "C416")]
+    #[test_case(CheckCode::C417, Path::new("C417.py"); "C417")]
+    #[test_case(CheckCode::D100, Path::new("D.py"); "D100")]
+    #[test_case(CheckCode::D101, Path::new("D.py"); "D101")]
+    #[test_case(CheckCode::D102, Path::new("D.py"); "D102")]
+    #[test_case(CheckCode::D103, Path::new("D.py"); "D103")]
+    #[test_case(CheckCode::D104, Path::new("D.py"); "D104")]
+    #[test_case(CheckCode::D105, Path::new("D.py"); "D105")]
+    #[test_case(CheckCode::D106, Path::new("D.py"); "D106")]
+    #[test_case(CheckCode::D107, Path::new("D.py"); "D107")]
+    #[test_case(CheckCode::D201, Path::new("D.py"); "D201")]
+    #[test_case(CheckCode::D202, Path::new("D.py"); "D202")]
+    #[test_case(CheckCode::D203, Path::new("D.py"); "D203")]
+    #[test_case(CheckCode::D204, Path::new("D.py"); "D204")]
+    #[test_case(CheckCode::D205, Path::new("D.py"); "D205")]
+    #[test_case(CheckCode::D206, Path::new("D.py"); "D206")]
+    #[test_case(CheckCode::D207, Path::new("D.py"); "D207")]
+    #[test_case(CheckCode::D208, Path::new("D.py"); "D208")]
+    #[test_case(CheckCode::D209, Path::new("D.py"); "D209")]
+    #[test_case(CheckCode::D210, Path::new("D.py"); "D210")]
+    #[test_case(CheckCode::D211, Path::new("D.py"); "D211")]
+    #[test_case(CheckCode::D212, Path::new("D.py"); "D212")]
+    #[test_case(CheckCode::D213, Path::new("D.py"); "D213")]
+    #[test_case(CheckCode::D214, Path::new("sections.py"); "D214")]
+    #[test_case(CheckCode::D215, Path::new("sections.py"); "D215")]
+    #[test_case(CheckCode::D300, Path::new("D.py"); "D300")]
+    #[test_case(CheckCode::D400, Path::new("D.py"); "D400")]
+    #[test_case(CheckCode::D402, Path::new("D.py"); "D402")]
+    #[test_case(CheckCode::D403, Path::new("D.py"); "D403")]
+    #[test_case(CheckCode::D404, Path::new("D.py"); "D404")]
+    #[test_case(CheckCode::D405, Path::new("sections.py"); "D405")]
+    #[test_case(CheckCode::D406, Path::new("sections.py"); "D406")]
+    #[test_case(CheckCode::D407, Path::new("sections.py"); "D407")]
+    #[test_case(CheckCode::D408, Path::new("sections.py"); "D408")]
+    #[test_case(CheckCode::D409, Path::new("sections.py"); "D409")]
+    #[test_case(CheckCode::D410, Path::new("sections.py"); "D410")]
+    #[test_case(CheckCode::D411, Path::new("sections.py"); "D411")]
+    #[test_case(CheckCode::D412, Path::new("sections.py"); "D412")]
+    #[test_case(CheckCode::D413, Path::new("sections.py"); "D413")]
+    #[test_case(CheckCode::D414, Path::new("sections.py"); "D414")]
+    #[test_case(CheckCode::D415, Path::new("D.py"); "D415")]
+    #[test_case(CheckCode::D416, Path::new("D.py"); "D416")]
+    #[test_case(CheckCode::D417, Path::new("sections.py"); "D417_0")]
+    #[test_case(CheckCode::D417, Path::new("canonical_numpy_examples.py"); "D417_1")]
+    #[test_case(CheckCode::D417, Path::new("canonical_google_examples.py"); "D417_2")]
+    #[test_case(CheckCode::D418, Path::new("D.py"); "D418")]
+    #[test_case(CheckCode::D419, Path::new("D.py"); "D419")]
+    #[test_case(CheckCode::E402, Path::new("E402.py"); "E402")]
+    #[test_case(CheckCode::E501, Path::new("E501.py"); "E501")]
+    #[test_case(CheckCode::E711, Path::new("E711.py"); "E711")]
+    #[test_case(CheckCode::E712, Path::new("E712.py"); "E712")]
+    #[test_case(CheckCode::E713, Path::new("E713.py"); "E713")]
+    #[test_case(CheckCode::E714, Path::new("E714.py"); "E714")]
+    #[test_case(CheckCode::E721, Path::new("E721.py"); "E721")]
+    #[test_case(CheckCode::E722, Path::new("E722.py"); "E722")]
+    #[test_case(CheckCode::E731, Path::new("E731.py"); "E731")]
+    #[test_case(CheckCode::E741, Path::new("E741.py"); "E741")]
+    #[test_case(CheckCode::E742, Path::new("E742.py"); "E742")]
+    #[test_case(CheckCode::E743, Path::new("E743.py"); "E743")]
+    #[test_case(CheckCode::E999, Path::new("E999.py"); "E999")]
+    #[test_case(CheckCode::F401, Path::new("F401_0.py"); "F401_0")]
+    #[test_case(CheckCode::F401, Path::new("F401_1.py"); "F401_1")]
+    #[test_case(CheckCode::F401, Path::new("F401_2.py"); "F401_2")]
+    #[test_case(CheckCode::F401, Path::new("F401_3.py"); "F401_3")]
+    #[test_case(CheckCode::F401, Path::new("F401_4.py"); "F401_4")]
+    #[test_case(CheckCode::F402, Path::new("F402.py"); "F402")]
+    #[test_case(CheckCode::F403, Path::new("F403.py"); "F403")]
+    #[test_case(CheckCode::F404, Path::new("F404.py"); "F404")]
+    #[test_case(CheckCode::F405, Path::new("F405.py"); "F405")]
+    #[test_case(CheckCode::F406, Path::new("F406.py"); "F406")]
+    #[test_case(CheckCode::F407, Path::new("F407.py"); "F407")]
+    #[test_case(CheckCode::F541, Path::new("F541.py"); "F541")]
+    #[test_case(CheckCode::F601, Path::new("F601.py"); "F601")]
+    #[test_case(CheckCode::F602, Path::new("F602.py"); "F602")]
+    #[test_case(CheckCode::F622, Path::new("F622.py"); "F622")]
+    #[test_case(CheckCode::F631, Path::new("F631.py"); "F631")]
+    #[test_case(CheckCode::F632, Path::new("F632.py"); "F632")]
+    #[test_case(CheckCode::F633, Path::new("F633.py"); "F633")]
+    #[test_case(CheckCode::F634, Path::new("F634.py"); "F634")]
+    #[test_case(CheckCode::F701, Path::new("F701.py"); "F701")]
+    #[test_case(CheckCode::F702, Path::new("F702.py"); "F702")]
+    #[test_case(CheckCode::F704, Path::new("F704.py"); "F704")]
+    #[test_case(CheckCode::F706, Path::new("F706.py"); "F706")]
+    #[test_case(CheckCode::F707, Path::new("F707.py"); "F707")]
+    #[test_case(CheckCode::F722, Path::new("F722.py"); "F722")]
+    #[test_case(CheckCode::F821, Path::new("F821.py"); "F821")]
+    #[test_case(CheckCode::F822, Path::new("F822.py"); "F822")]
+    #[test_case(CheckCode::F823, Path::new("F823.py"); "F823")]
+    #[test_case(CheckCode::F831, Path::new("F831.py"); "F831")]
+    #[test_case(CheckCode::F841, Path::new("F841.py"); "F841")]
+    #[test_case(CheckCode::F901, Path::new("F901.py"); "F901")]
+    #[test_case(CheckCode::N801, Path::new("N801.py"); "N801")]
+    #[test_case(CheckCode::N802, Path::new("N802.py"); "N802")]
+    #[test_case(CheckCode::N803, Path::new("N803.py"); "N803")]
+    #[test_case(CheckCode::N804, Path::new("N804.py"); "N804")]
+    #[test_case(CheckCode::N805, Path::new("N805.py"); "N805")]
+    #[test_case(CheckCode::T201, Path::new("T201.py"); "T201")]
+    #[test_case(CheckCode::T203, Path::new("T203.py"); "T203")]
+    #[test_case(CheckCode::U001, Path::new("U001.py"); "U001")]
+    #[test_case(CheckCode::U002, Path::new("U002.py"); "U002")]
+    #[test_case(CheckCode::U003, Path::new("U003.py"); "U003")]
+    #[test_case(CheckCode::U004, Path::new("U004.py"); "U004")]
+    #[test_case(CheckCode::U005, Path::new("U005.py"); "U005")]
+    #[test_case(CheckCode::U006, Path::new("U006.py"); "U006")]
+    #[test_case(CheckCode::U007, Path::new("U007.py"); "U007")]
+    #[test_case(CheckCode::U008, Path::new("U008.py"); "U008")]
+    #[test_case(CheckCode::W292, Path::new("W292_0.py"); "W292_0")]
+    #[test_case(CheckCode::W292, Path::new("W292_1.py"); "W292_1")]
+    #[test_case(CheckCode::W292, Path::new("W292_2.py"); "W292_2")]
+    fn checks(check_code: CheckCode, path: &Path) -> Result<()> {
+        let snapshot = format!("{}_{}", check_code.as_ref(), path.to_string_lossy());
         let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E402.py"),
-            &settings::Settings::for_rule(CheckCode::E402),
+            Path::new("./resources/test/fixtures").join(path).as_path(),
+            &settings::Settings::for_rule(check_code.clone()),
             &fixer::Mode::Generate,
         )?;
         checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e501() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E501.py"),
-            &settings::Settings::for_rule(CheckCode::E501),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e711() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E711.py"),
-            &settings::Settings::for_rule(CheckCode::E711),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e712() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E712.py"),
-            &settings::Settings::for_rule(CheckCode::E712),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e713() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E713.py"),
-            &settings::Settings::for_rule(CheckCode::E713),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e721() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E721.py"),
-            &settings::Settings::for_rule(CheckCode::E721),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e722() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E722.py"),
-            &settings::Settings::for_rule(CheckCode::E722),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e714() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E714.py"),
-            &settings::Settings::for_rule(CheckCode::E714),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e731() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E731.py"),
-            &settings::Settings::for_rule(CheckCode::E731),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e741() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E741.py"),
-            &settings::Settings::for_rule(CheckCode::E741),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e742() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E742.py"),
-            &settings::Settings::for_rule(CheckCode::E742),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e743() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E743.py"),
-            &settings::Settings::for_rule(CheckCode::E743),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f401() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F401.py"),
-            &settings::Settings::for_rule(CheckCode::F401),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f402() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F402.py"),
-            &settings::Settings::for_rule(CheckCode::F402),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f403() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F403.py"),
-            &settings::Settings::for_rule(CheckCode::F403),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f404() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F404.py"),
-            &settings::Settings::for_rule(CheckCode::F404),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f405() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F405.py"),
-            &settings::Settings::for_rule(CheckCode::F405),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f406() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F406.py"),
-            &settings::Settings::for_rule(CheckCode::F406),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f407() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F407.py"),
-            &settings::Settings::for_rule(CheckCode::F407),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f541() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F541.py"),
-            &settings::Settings::for_rule(CheckCode::F541),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f601() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F601.py"),
-            &settings::Settings::for_rule(CheckCode::F601),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f602() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F602.py"),
-            &settings::Settings::for_rule(CheckCode::F602),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f622() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F622.py"),
-            &settings::Settings::for_rule(CheckCode::F622),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f631() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F631.py"),
-            &settings::Settings::for_rule(CheckCode::F631),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f632() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F632.py"),
-            &settings::Settings::for_rule(CheckCode::F632),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f633() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F633.py"),
-            &settings::Settings::for_rule(CheckCode::F633),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f634() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F634.py"),
-            &settings::Settings::for_rule(CheckCode::F634),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f701() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F701.py"),
-            &settings::Settings::for_rule(CheckCode::F701),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f702() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F702.py"),
-            &settings::Settings::for_rule(CheckCode::F702),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f704() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F704.py"),
-            &settings::Settings::for_rule(CheckCode::F704),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f706() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F706.py"),
-            &settings::Settings::for_rule(CheckCode::F706),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f707() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F707.py"),
-            &settings::Settings::for_rule(CheckCode::F707),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f722() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F722.py"),
-            &settings::Settings::for_rule(CheckCode::F722),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f821() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F821.py"),
-            &settings::Settings::for_rule(CheckCode::F821),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f822() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F822.py"),
-            &settings::Settings::for_rule(CheckCode::F822),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f823() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F823.py"),
-            &settings::Settings::for_rule(CheckCode::F823),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f831() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F831.py"),
-            &settings::Settings::for_rule(CheckCode::F831),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f841() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F841.py"),
-            &settings::Settings::for_rule(CheckCode::F841),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
+        insta::assert_yaml_snapshot!(snapshot, checks);
         Ok(())
     }
 
@@ -666,18 +398,6 @@ mod tests {
         Ok(())
     }
 
-    #[test]
-    fn f901() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F901.py"),
-            &settings::Settings::for_rule(CheckCode::F901),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
     #[test]
     fn m001() -> Result<()> {
         let mut checks = check_path(
@@ -713,196 +433,4 @@ mod tests {
         insta::assert_yaml_snapshot!(checks);
         Ok(())
     }
-
-    #[test]
-    fn e999() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E999.py"),
-            &settings::Settings::for_rule(CheckCode::E999),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn a001() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/A001.py"),
-            &settings::Settings::for_rule(CheckCode::A001),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn a002() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/A002.py"),
-            &settings::Settings::for_rule(CheckCode::A002),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn a003() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/A003.py"),
-            &settings::Settings::for_rule(CheckCode::A003),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn c400() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/C400.py"),
-            &settings::Settings::for_rule(CheckCode::C400),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn c401() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/C401.py"),
-            &settings::Settings::for_rule(CheckCode::C401),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn c403() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/C403.py"),
-            &settings::Settings::for_rule(CheckCode::C403),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn c404() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/C404.py"),
-            &settings::Settings::for_rule(CheckCode::C404),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn spr001() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/SPR001.py"),
-            &settings::Settings::for_rule(CheckCode::SPR001),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn t201() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/T201.py"),
-            &settings::Settings::for_rule(CheckCode::T201),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn t203() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/T203.py"),
-            &settings::Settings::for_rule(CheckCode::T203),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn u001() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/U001.py"),
-            &settings::Settings::for_rule(CheckCode::U001),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn u002() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/U002.py"),
-            &settings::Settings::for_rule(CheckCode::U002),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn u003() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/U003.py"),
-            &settings::Settings::for_rule(CheckCode::U003),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn u004() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/U004.py"),
-            &settings::Settings::for_rule(CheckCode::U004),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn u005() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/U005.py"),
-            &settings::Settings::for_rule(CheckCode::U005),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
 }

src/main.rs

@@ -1,4 +1,4 @@
-use std::io;
+use std::io::{self, Read};
 use std::path::{Path, PathBuf};
 use std::process::ExitCode;
 use std::sync::mpsc::channel;
@@ -9,9 +9,11 @@ use clap::Parser;
 use colored::Colorize;
 use log::{debug, error};
 use notify::{raw_watcher, RecursiveMode, Watcher};
+#[cfg(not(target_family = "wasm"))]
 use rayon::prelude::*;
 use walkdir::DirEntry;
 
+#[cfg(not(target_family = "wasm"))]
 use ruff::cache;
 use ruff::checks::CheckCode;
 use ruff::checks::CheckKind;
@@ -19,7 +21,7 @@ use ruff::cli::{warn_on, Cli, Warnable};
 use ruff::fs::iter_python_files;
 use ruff::linter::add_noqa_to_path;
 use ruff::linter::autoformat_path;
-use ruff::linter::lint_path;
+use ruff::linter::{lint_path, lint_stdin};
 use ruff::logging::set_up_logging;
 use ruff::message::Message;
 use ruff::printer::{Printer, SerializationFormat};
@@ -29,9 +31,24 @@ use ruff::settings::RawSettings;
 use ruff::settings::{FilePattern, PerFileIgnore, Settings};
 use ruff::tell_user;
 
+#[cfg(feature = "update-informer")]
 const CARGO_PKG_NAME: &str = env!("CARGO_PKG_NAME");
+#[cfg(feature = "update-informer")]
 const CARGO_PKG_VERSION: &str = env!("CARGO_PKG_VERSION");
 
+/// Shim that calls par_iter except for wasm because there's no wasm support in rayon yet
+/// (there is a shim to be used for the web, but it requires js cooperation)
+/// Unfortunately, ParallelIterator does not implement Iterator so the signatures diverge
+#[cfg(not(target_family = "wasm"))]
+fn par_iter<T: Sync>(iterable: &Vec<T>) -> impl ParallelIterator<Item = &T> {
+    iterable.par_iter()
+}
+
+#[cfg(target_family = "wasm")]
+fn par_iter<T: Sync>(iterable: &Vec<T>) -> impl Iterator<Item = &T> {
+    iterable.iter()
+}
+
 #[cfg(feature = "update-informer")]
 fn check_for_updates() {
     use update_informer::{registry, Check};
@@ -75,6 +92,19 @@ fn show_files(files: &[PathBuf], settings: &Settings) {
     }
 }
 
+fn read_from_stdin() -> Result<String> {
+    let mut buffer = String::new();
+    io::stdin().lock().read_to_string(&mut buffer)?;
+    Ok(buffer)
+}
+
+fn run_once_stdin(settings: &Settings, filename: &Path, autofix: bool) -> Result<Vec<Message>> {
+    let stdin = read_from_stdin()?;
+    let mut messages = lint_stdin(filename, &stdin, settings, &autofix.into())?;
+    messages.sort_unstable();
+    Ok(messages)
+}
+
 fn run_once(
     files: &[PathBuf],
     settings: &Settings,
@@ -91,8 +121,7 @@ fn run_once(
     debug!("Identified files to lint in: {:?}", duration);
 
     let start = Instant::now();
-    let mut messages: Vec<Message> = paths
-        .par_iter()
+    let mut messages: Vec<Message> = par_iter(&paths)
         .map(|entry| {
             match entry {
                 Ok(entry) => {
@@ -147,8 +176,7 @@ fn add_noqa(files: &[PathBuf], settings: &Settings) -> Result<usize> {
     debug!("Identified files to lint in: {:?}", duration);
 
     let start = Instant::now();
-    let modifications: usize = paths
-        .par_iter()
+    let modifications: usize = par_iter(&paths)
         .map(|entry| match entry {
             Ok(entry) => {
                 let path = entry.path();
@@ -177,8 +205,7 @@ fn autoformat(files: &[PathBuf], settings: &Settings) -> Result<usize> {
     debug!("Identified files to lint in: {:?}", duration);
 
     let start = Instant::now();
-    let modifications = paths
-        .par_iter()
+    let modifications = par_iter(&paths)
         .map(|entry| {
             let path = entry.path();
             autoformat_path(path)
@@ -203,7 +230,9 @@ fn inner_main() -> Result<ExitCode> {
         Some(path) => debug!("Found project root at: {:?}", path),
         None => debug!("Unable to identify project root; assuming current directory..."),
     };
-    let pyproject = pyproject::find_pyproject_toml(&project_root);
+    let pyproject = cli
+        .config
+        .or_else(|| pyproject::find_pyproject_toml(&project_root));
     match &pyproject {
         Some(path) => debug!("Found pyproject.toml at: {:?}", path),
         None => debug!("Unable to find pyproject.toml; using default settings..."),
@@ -287,6 +316,7 @@ fn inner_main() -> Result<ExitCode> {
         return Ok(ExitCode::SUCCESS);
     }
 
+    #[cfg(not(target_family = "wasm"))]
     cache::init()?;
 
     let mut printer = Printer::new(cli.format, cli.verbose);
@@ -352,13 +382,30 @@ fn inner_main() -> Result<ExitCode> {
             println!("Formatted {modifications} files.");
         }
     } else {
-        let messages = run_once(&cli.files, &settings, !cli.no_cache, cli.fix)?;
-        if !cli.quiet {
+        let (messages, should_print_messages, should_check_updates) =
+            if cli.files == vec![PathBuf::from("-")] {
+                let filename = cli.stdin_filename.unwrap_or_else(|| "-".to_string());
+                let path = Path::new(&filename);
+                (
+                    run_once_stdin(&settings, path, cli.fix)?,
+                    !cli.quiet && !cli.fix,
+                    false,
+                )
+            } else {
+                (
+                    run_once(&cli.files, &settings, !cli.no_cache, cli.fix)?,
+                    !cli.quiet,
+                    !cli.quiet,
+                )
+            };
+        if should_print_messages {
             printer.write_once(&messages)?;
         }
 
         #[cfg(feature = "update-informer")]
-        check_for_updates();
+        if should_check_updates {
+            check_for_updates();
+        }
 
         if messages.iter().any(|message| !message.fixed) && !cli.exit_zero {
             return Ok(ExitCode::FAILURE);

src/message.rs

@@ -45,7 +45,7 @@ impl fmt::Display for Message {
             ":".cyan(),
             self.location.column(),
             ":".cyan(),
-            self.kind.code().as_str().red().bold(),
+            self.kind.code().as_ref().red().bold(),
             self.kind.body()
         )
     }

src/noqa.rs

@@ -81,7 +81,7 @@ pub fn extract_noqa_line_for(lxr: &[LexResult]) -> Vec<usize> {
 }
 
 fn add_noqa_inner(
-    checks: &Vec<Check>,
+    checks: &[Check],
     contents: &str,
     noqa_line_for: &[usize],
 ) -> Result<(usize, String)> {
@@ -125,7 +125,7 @@ fn add_noqa_inner(
                     Directive::All(start, _) => output.push_str(&line[..start]),
                     Directive::Codes(start, _, _) => output.push_str(&line[..start]),
                 };
-                let codes: Vec<&str> = codes.iter().map(|code| code.as_str()).collect();
+                let codes: Vec<&str> = codes.iter().map(|code| code.as_ref()).collect();
                 output.push_str("  # noqa: ");
                 output.push_str(&codes.join(", "));
                 output.push('\n');
@@ -138,7 +138,7 @@ fn add_noqa_inner(
 }
 
 pub fn add_noqa(
-    checks: &Vec<Check>,
+    checks: &[Check],
     contents: &str,
     noqa_line_for: &[usize],
     path: &Path,
@@ -150,12 +150,12 @@ pub fn add_noqa(
 
 #[cfg(test)]
 mod tests {
-    use crate::ast::types::Range;
     use anyhow::Result;
     use rustpython_parser::ast::Location;
     use rustpython_parser::lexer;
     use rustpython_parser::lexer::LexResult;
 
+    use crate::ast::types::Range;
     use crate::checks::{Check, CheckKind};
     use crate::noqa::{add_noqa_inner, extract_noqa_line_for};
 

src/pep8_naming/checks.rs

@@ -0,0 +1,99 @@
+use rustpython_ast::{Arguments, Expr, ExprKind, Stmt};
+
+use crate::ast::types::{Range, Scope, ScopeKind};
+use crate::checks::{Check, CheckKind};
+
+pub fn invalid_class_name(class_def: &Stmt, name: &str) -> Option<Check> {
+    let stripped = name.strip_prefix('_').unwrap_or(name);
+    if !stripped
+        .chars()
+        .next()
+        .map(|c| c.is_uppercase())
+        .unwrap_or(false)
+        || stripped.contains('_')
+    {
+        return Some(Check::new(
+            CheckKind::InvalidClassName(name.to_string()),
+            Range::from_located(class_def),
+        ));
+    }
+    None
+}
+
+pub fn invalid_function_name(func_def: &Stmt, name: &str) -> Option<Check> {
+    if name.chars().any(|c| c.is_uppercase()) {
+        return Some(Check::new(
+            CheckKind::InvalidFunctionName(name.to_string()),
+            Range::from_located(func_def),
+        ));
+    }
+    None
+}
+
+pub fn invalid_argument_name(location: Range, name: &str) -> Option<Check> {
+    if name.chars().any(|c| c.is_uppercase()) {
+        return Some(Check::new(
+            CheckKind::InvalidArgumentName(name.to_string()),
+            location,
+        ));
+    }
+    None
+}
+
+pub fn invalid_first_argument_name_for_class_method(
+    scope: &Scope,
+    decorator_list: &[Expr],
+    args: &Arguments,
+) -> Option<Check> {
+    if !matches!(scope.kind, ScopeKind::Class) {
+        return None;
+    }
+
+    if decorator_list.iter().any(|decorator| {
+        if let ExprKind::Name { id, .. } = &decorator.node {
+            id == "classmethod"
+        } else {
+            false
+        }
+    }) {
+        if let Some(arg) = args.args.first() {
+            if arg.node.arg != "cls" {
+                return Some(Check::new(
+                    CheckKind::InvalidFirstArgumentNameForClassMethod,
+                    Range::from_located(arg),
+                ));
+            }
+        }
+    }
+    None
+}
+
+pub fn invalid_first_argument_name_for_method(
+    scope: &Scope,
+    decorator_list: &[Expr],
+    args: &Arguments,
+) -> Option<Check> {
+    if !matches!(scope.kind, ScopeKind::Class) {
+        return None;
+    }
+
+    if decorator_list.iter().any(|decorator| {
+        if let ExprKind::Name { id, .. } = &decorator.node {
+            id == "classmethod" || id == "staticmethod"
+        } else {
+            false
+        }
+    }) {
+        return None;
+    }
+
+    if let Some(arg) = args.args.first() {
+        if arg.node.arg != "self" {
+            return Some(Check::new(
+                CheckKind::InvalidFirstArgumentNameForMethod,
+                Range::from_located(arg),
+            ));
+        }
+    }
+    None
+}

src/pep8_naming/mod.rs

@@ -0,0 +1 @@
+pub mod checks;

src/plugins/assert_equals.rs

@@ -1,23 +0,0 @@
-use rustpython_ast::{Expr, Location};
-
-use crate::ast::checks;
-use crate::autofix::fixer;
-use crate::check_ast::Checker;
-use crate::checks::Fix;
-
-pub fn assert_equals(checker: &mut Checker, expr: &Expr) {
-    if let Some(mut check) = checks::check_assert_equals(expr) {
-        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-            check.amend(Fix {
-                content: "assertEqual".to_string(),
-                location: Location::new(expr.location.row(), expr.location.column() + 1),
-                end_location: Location::new(
-                    expr.location.row(),
-                    expr.location.column() + 1 + "assertEquals".len(),
-                ),
-                applied: false,
-            });
-        }
-        checker.add_check(check);
-    }
-}

src/plugins/unnecessary_abspath.rs

@@ -1,25 +0,0 @@
-use rustpython_ast::Expr;
-
-use crate::ast::checks;
-use crate::ast::types::{CheckLocator, Range};
-use crate::autofix::fixer;
-use crate::check_ast::Checker;
-use crate::checks::Fix;
-
-pub fn unnecessary_abspath(checker: &mut Checker, expr: &Expr, func: &Expr, args: &Vec<Expr>) {
-    if let Some(mut check) = checks::check_unnecessary_abspath(
-        func,
-        args,
-        checker.locate_check(Range::from_located(expr)),
-    ) {
-        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-            check.amend(Fix {
-                content: "__file__".to_string(),
-                location: expr.location,
-                end_location: expr.end_location,
-                applied: false,
-            });
-        }
-        checker.add_check(check);
-    }
-}

src/printer.rs

@@ -50,14 +50,14 @@ impl Printer {
                     serde_json::to_string_pretty(
                         &messages
                             .iter()
-                            .map(|m| ExpandedMessage {
-                                kind: &m.kind,
-                                code: m.kind.code(),
-                                message: m.kind.body(),
-                                fixed: m.fixed,
-                                location: m.location,
-                                end_location: m.end_location,
-                                filename: &m.filename,
+                            .map(|message| ExpandedMessage {
+                                kind: &message.kind,
+                                code: message.kind.code(),
+                                message: message.kind.body(),
+                                fixed: message.fixed,
+                                location: message.location,
+                                end_location: message.end_location,
+                                filename: &message.filename,
                             })
                             .collect::<Vec<_>>()
                     )?
@@ -104,6 +104,7 @@ impl Printer {
     }
 
     pub fn clear_screen(&mut self) -> Result<()> {
+        #[cfg(not(target_family = "wasm"))]
         clearscreen::clear()?;
         Ok(())
     }

src/pycodestyle/checks.rs

@@ -0,0 +1,238 @@
+use itertools::izip;
+use rustpython_parser::ast::{Cmpop, Constant, Expr, ExprKind, Unaryop};
+
+use crate::ast::types::{CheckLocator, Range};
+use crate::checks::{Check, CheckKind, RejectedCmpop};
+
+fn is_ambiguous_name(name: &str) -> bool {
+    name == "l" || name == "I" || name == "O"
+}
+
+/// Check AmbiguousVariableName compliance.
+pub fn ambiguous_variable_name(name: &str, location: Range) -> Option<Check> {
+    if is_ambiguous_name(name) {
+        Some(Check::new(
+            CheckKind::AmbiguousVariableName(name.to_string()),
+            location,
+        ))
+    } else {
+        None
+    }
+}
+
+/// Check AmbiguousClassName compliance.
+pub fn ambiguous_class_name(name: &str, location: Range) -> Option<Check> {
+    if is_ambiguous_name(name) {
+        Some(Check::new(
+            CheckKind::AmbiguousClassName(name.to_string()),
+            location,
+        ))
+    } else {
+        None
+    }
+}
+
+/// Check AmbiguousFunctionName compliance.
+pub fn ambiguous_function_name(name: &str, location: Range) -> Option<Check> {
+    if is_ambiguous_name(name) {
+        Some(Check::new(
+            CheckKind::AmbiguousFunctionName(name.to_string()),
+            location,
+        ))
+    } else {
+        None
+    }
+}
+
+/// Check DoNotAssignLambda compliance.
+pub fn do_not_assign_lambda(value: &Expr, location: Range) -> Option<Check> {
+    if let ExprKind::Lambda { .. } = &value.node {
+        Some(Check::new(CheckKind::DoNotAssignLambda, location))
+    } else {
+        None
+    }
+}
+
+/// Check NotInTest and NotIsTest compliance.
+pub fn not_tests(
+    op: &Unaryop,
+    operand: &Expr,
+    check_not_in: bool,
+    check_not_is: bool,
+    locator: &dyn CheckLocator,
+) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
+    if matches!(op, Unaryop::Not) {
+        if let ExprKind::Compare { ops, .. } = &operand.node {
+            for op in ops {
+                match op {
+                    Cmpop::In => {
+                        if check_not_in {
+                            checks.push(Check::new(
+                                CheckKind::NotInTest,
+                                locator.locate_check(Range::from_located(operand)),
+                            ));
+                        }
+                    }
+                    Cmpop::Is => {
+                        if check_not_is {
+                            checks.push(Check::new(
+                                CheckKind::NotIsTest,
+                                locator.locate_check(Range::from_located(operand)),
+                            ));
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+
+    checks
+}
+
+/// Check TrueFalseComparison and NoneComparison compliance.
+pub fn literal_comparisons(
+    left: &Expr,
+    ops: &[Cmpop],
+    comparators: &[Expr],
+    check_none_comparisons: bool,
+    check_true_false_comparisons: bool,
+    locator: &dyn CheckLocator,
+) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
+    let op = ops.first().unwrap();
+    let comparator = left;
+
+    // Check `left`.
+    if check_none_comparisons
+        && matches!(
+            comparator.node,
+            ExprKind::Constant {
+                value: Constant::None,
+                kind: None
+            }
+        )
+    {
+        if matches!(op, Cmpop::Eq) {
+            checks.push(Check::new(
+                CheckKind::NoneComparison(RejectedCmpop::Eq),
+                locator.locate_check(Range::from_located(comparator)),
+            ));
+        }
+        if matches!(op, Cmpop::NotEq) {
+            checks.push(Check::new(
+                CheckKind::NoneComparison(RejectedCmpop::NotEq),
+                locator.locate_check(Range::from_located(comparator)),
+            ));
+        }
+    }
+
+    if check_true_false_comparisons {
+        if let ExprKind::Constant {
+            value: Constant::Bool(value),
+            kind: None,
+        } = comparator.node
+        {
+            if matches!(op, Cmpop::Eq) {
+                checks.push(Check::new(
+                    CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
+                    locator.locate_check(Range::from_located(comparator)),
+                ));
+            }
+            if matches!(op, Cmpop::NotEq) {
+                checks.push(Check::new(
+                    CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
+                    locator.locate_check(Range::from_located(comparator)),
+                ));
+            }
+        }
+    }
+
+    // Check each comparator in order.
+    for (op, comparator) in izip!(ops, comparators) {
+        if check_none_comparisons
+            && matches!(
+                comparator.node,
+                ExprKind::Constant {
+                    value: Constant::None,
+                    kind: None
+                }
+            )
+        {
+            if matches!(op, Cmpop::Eq) {
+                checks.push(Check::new(
+                    CheckKind::NoneComparison(RejectedCmpop::Eq),
+                    locator.locate_check(Range::from_located(comparator)),
+                ));
+            }
+            if matches!(op, Cmpop::NotEq) {
+                checks.push(Check::new(
+                    CheckKind::NoneComparison(RejectedCmpop::NotEq),
+                    locator.locate_check(Range::from_located(comparator)),
+                ));
+            }
+        }
+
+        if check_true_false_comparisons {
+            if let ExprKind::Constant {
+                value: Constant::Bool(value),
+                kind: None,
+            } = comparator.node
+            {
+                if matches!(op, Cmpop::Eq) {
+                    checks.push(Check::new(
+                        CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
+                        locator.locate_check(Range::from_located(comparator)),
+                    ));
+                }
+                if matches!(op, Cmpop::NotEq) {
+                    checks.push(Check::new(
+                        CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
+                        locator.locate_check(Range::from_located(comparator)),
+                    ));
+                }
+            }
+        }
+    }
+
+    checks
+}
+
+/// Check TypeComparison compliance.
+pub fn type_comparison(ops: &[Cmpop], comparators: &[Expr], location: Range) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
+    for (op, right) in izip!(ops, comparators) {
+        if matches!(op, Cmpop::Is | Cmpop::IsNot | Cmpop::Eq | Cmpop::NotEq) {
+            match &right.node {
+                ExprKind::Call { func, args, .. } => {
+                    if let ExprKind::Name { id, .. } = &func.node {
+                        // Ex) type(False)
+                        if id == "type" {
+                            if let Some(arg) = args.first() {
+                                // Allow comparison for types which are not obvious.
+                                if !matches!(arg.node, ExprKind::Name { .. }) {
+                                    checks.push(Check::new(CheckKind::TypeComparison, location));
+                                }
+                            }
+                        }
+                    }
+                }
+                ExprKind::Attribute { value, .. } => {
+                    if let ExprKind::Name { id, .. } = &value.node {
+                        // Ex) types.IntType
+                        if id == "types" {
+                            checks.push(Check::new(CheckKind::TypeComparison, location));
+                        }
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+
+    checks
+}

src/pycodestyle/mod.rs

@@ -0,0 +1 @@
+pub mod checks;

src/pydocstyle/mod.rs

@@ -0,0 +1 @@
+pub mod plugins;