Compile for WASM

- wasm-pack build --target web
- rm -rf demo/src/pkg && cp -r pkg demo/src/pkg
- npm run dev

.github/workflows/ci.yaml

@@ -2,16 +2,16 @@ name: CI
 
 on:
   push:
-    branches: [ main ]
+    branches: [main]
   pull_request:
-    branches: [ main ]
+    branches: [main]
 
 jobs:
   cargo_build:
     name: "cargo build"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -33,7 +33,7 @@ jobs:
     name: "cargo fmt"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -55,7 +55,7 @@ jobs:
     name: "cargo clippy"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -77,7 +77,7 @@ jobs:
     name: "cargo test"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -99,13 +99,13 @@ jobs:
     name: "maturin build"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
       - uses: actions/setup-python@v4
         with:
-          python-version: '3.10'
+          python-version: "3.10"
       - run: pip install maturin
       - uses: actions/cache@v3
         env:

.github/workflows/release.yaml

@@ -1,6 +1,8 @@
 name: Release
 
 on:
+  pull_request:
+    branches: [main]
   create:
     tags:
       - v*
@@ -14,7 +16,7 @@ env:
   PYTHON_VERSION: "3.7" # to build abi3 wheels
 
 jobs:
-  macos:
+  macos-x86_64:
     runs-on: macos-latest
     steps:
       - uses: actions/checkout@v3
@@ -37,6 +39,25 @@ jobs:
       - name: Install built wheel - x86_64
         run: |
           pip install dist/${{ env.PACKAGE_NAME }}-*.whl --force-reinstall
+      - name: Upload wheels
+        uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: dist
+  macos-universal:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+          architecture: x64
+      - name: Install Rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+          default: true
       - name: Build wheels - universal2
         uses: messense/maturin-action@v1
         with:
@@ -127,7 +148,7 @@ jobs:
         with:
           target: ${{ matrix.target }}
           manylinux: auto
-          args: --release --out dist
+          args: --no-default-features --release --out dist
           maturin-version: "v0.13.0"
       - uses: uraimo/run-on-arch-action@v2.0.5
         if: matrix.target != 'ppc64'
@@ -227,9 +248,9 @@ jobs:
         os: [ubuntu-latest, macos-latest]
         target: [x86_64, aarch64]
         python-version:
-          - '3.7'
-          - '3.8'
-          - '3.9'
+          - "3.7"
+          - "3.8"
+          - "3.9"
         exclude:
           - os: macos-latest
             target: aarch64
@@ -259,7 +280,8 @@ jobs:
     name: Release
     runs-on: ubuntu-latest
     needs:
-      - macos
+      - macos-universal
+      - macos-x86_64
       - windows
       - linux
       - linux-cross

.gitignore

@@ -1,5 +1,5 @@
 # Local cache
-.cache
+.ruff_cache
 resources/test/cpython
 
 ###

.pre-commit-config.yaml

@@ -0,0 +1,5 @@
+repos:
+  - repo: https://github.com/charliermarsh/ruff-pre-commit
+    rev: v0.0.40
+    hooks:
+      - id: lint

Cargo.toml

@@ -1,36 +1,40 @@
 [package]
 name = "ruff"
-version = "0.0.22"
+version = "0.0.44"
 edition = "2021"
 
 [lib]
 name = "ruff"
+crate-type = ["cdylib"]
 
 [dependencies]
+wasm-bindgen = "0.2.83"
 anyhow = { version = "1.0.60" }
-bincode = { version = "1.3.3" }
-cacache = { version = "10.0.1" }
 chrono = { version = "0.4.21" }
-clap = { version = "3.2.16", features = ["derive"] }
-clearscreen = { version = "1.0.10" }
-colored = { version = "2.0.0" }
-common-path = { version = "1.0.0" }
-dirs = { version = "4.0.0" }
 fern = { version = "0.6.1" }
 filetime = { version = "0.2.17" }
-glob = { version = "0.3.0"}
+glob = { version = "0.3.0" }
+itertools = { version = "0.10.3" }
 log = { version = "0.4.17" }
-notify = { version = "4.0.17" }
+once_cell = { version = "1.13.1" }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
-rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "1613f6c6990011a4bc559e79aaf28d715f9f729b" }
+rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "7d21c6923a506e79cc041708d83cef925efd33f4" }
 serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
 toml = { version = "0.5.9" }
-walkdir = { version = "2.3.2" }
+
+[dev-dependencies]
+insta = { version = "1.19.1", features = ["yaml"] }
 
 [profile.release]
 panic = "abort"
 lto = "thin"
 codegen-units = 1
 opt-level = 3
+
+[profile.dev.package.insta]
+opt-level = 3
+
+[profile.dev.package.similar]
+opt-level = 3

README.md

@@ -1,7 +1,9 @@
 # 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)
+[![image](https://img.shields.io/pypi/pyversions/ruff.svg)](https://pypi.python.org/pypi/ruff)
 [![Actions status](https://github.com/charliermarsh/ruff/workflows/CI/badge.svg)](https://github.com/charliermarsh/ruff/actions)
-[![PyPI version](https://badge.fury.io/py/ruff.svg)](https://badge.fury.io/py/ruff)
 
 An extremely fast Python linter, written in Rust.
 
@@ -17,11 +19,10 @@ An extremely fast Python linter, written in Rust.
 - 🐍 Installable via `pip`
 - 🤝 Python 3.10 compatibility
 - 🛠️ `pyproject.toml` support
-- 📦 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired cache semantics
-- 👀 [TypeScript](https://www.typescriptlang.org/docs/handbook/configuring-watch.html)-inspired `--watch` semantics
-
-_ruff is a proof-of-concept and not yet intended for production use. It supports only a small subset
-of the Flake8 rules, and may crash on your codebase._
+- 📦 [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#caching)-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
 
 Read the [launch blog post](https://notes.crmarsh.com/python-tooling-could-be-much-much-faster).
 
@@ -51,6 +52,16 @@ You can run ruff in `--watch` mode to automatically re-run on-change:
 ruff path/to/code/ --watch
 ```
 
+ruff also works with [pre-commit](https://pre-commit.com):
+
+```yaml
+repos:
+  - repo: https://github.com/charliermarsh/ruff-pre-commit
+    rev: v0.0.40
+    hooks:
+      - id: lint
+```
+
 ## Configuration
 
 ruff is configurable both via `pyproject.toml` and the command line.
@@ -75,7 +86,7 @@ ruff path/to/code/ --select F401 F403
 See `ruff --help` for more:
 
 ```shell
-ruff
+ruff (v0.0.44) 0.0.44
 An extremely fast Python linter.
 
 USAGE:
@@ -85,17 +96,120 @@ ARGS:
     <FILES>...
 
 OPTIONS:
-    -e, --exit-zero             Exit with status code "0", even upon detecting errors
-    -h, --help                  Print help information
-        --ignore <IGNORE>...    Comma-separated list of error codes to ignore
-    -n, --no-cache              Disable cache reads
-    -q, --quiet                 Disable all logging (but still exit with status code "1" upon
-                                detecting errors)
-        --select <SELECT>...    Comma-separated list of error codes to enable
-    -v, --verbose               Enable verbose logging
-    -w, --watch                 Run in watch mode by re-running whenever files change
+    -e, --exit-zero
+            Exit with status code "0", even upon detecting errors
+        --exclude <EXCLUDE>...
+            List of paths, used to exclude files and/or directories from checks
+        --extend-exclude <EXTEND_EXCLUDE>...
+            Like --exclude, but adds additional files and directories on top of the excluded ones
+    -f, --fix
+            Attempt to automatically fix lint errors
+        --format <FORMAT>
+            Output serialization format for error messages [default: text] [possible values: text,
+            json]
+    -h, --help
+            Print help information
+        --ignore <IGNORE>...
+            List of error codes to ignore
+    -n, --no-cache
+            Disable cache reads
+    -q, --quiet
+            Disable all logging (but still exit with status code "1" upon detecting errors)
+        --select <SELECT>...
+            List of error codes to enable
+        --show-files
+            See the files ruff will be run against with the current configuration options
+        --show-settings
+            See ruff's settings
+    -v, --verbose
+            Enable verbose logging
+    -V, --version
+            Print version information
+    -w, --watch
+            Run in watch mode by re-running whenever files change
 ```
 
+Exclusions are based on globs, and can be either:
+
+- Single-path patterns, like `.mypy_cache` (to exclude any directory named `.mypy_cache` in the
+  tree), `foo.py` (to exclude any file named `foo.py`), or `foo_*.py` (to exclude any file matching
+  `foo_*.py` ).
+- Relative patterns, like `directory/foo.py` (to exclude that specific file) or `directory/*.py`
+  (to exclude any Python files in `directory`). Note that these paths are relative to the
+  project root (e.g., the directory containing your `pyproject.toml`).
+
+### Compatibility with Black
+
+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.)
+
+Beyond rule-set parity, ruff suffers from the following limitations vis-à-vis Flake8:
+
+1. Flake8 has a plugin architecture and supports writing custom lint rules.
+2. Flake8 supports a wider range of `noqa` patterns, such as per-file ignores defined in `.flake8`.
+3. ruff does not yet support parenthesized context managers.
+
+## Rules
+
+| 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 | ... |
+| 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 | TooManyExpressionsInStarredAssignment | 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 ==/!= 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 | a `yield` or `yield from` statement outside of a function/method |
+| F706 | ReturnOutsideFunction | a `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` |
+| R001 | UselessObjectInheritance | Class `...` inherits from object |
+| R002 | NoAssertEquals | `assertEquals` is deprecated, use `assertEqual` instead |
+
 ## Development
 
 ruff is written in Rust (1.63.0). You'll need to install the [Rust toolchain](https://www.rust-lang.org/tools/install)
@@ -104,7 +218,7 @@ for development.
 Assuming you have `cargo` installed, you can run:
 
 ```shell
-cargo run resources/test/src
+cargo run resources/test/fixtures
 cargo fmt
 cargo clippy
 cargo test
@@ -128,49 +242,25 @@ git clone --branch 3.10 https://github.com/python/cpython.git resources/test/cpy
 Add this `pyproject.toml` to the CPython directory:
 
 ```toml
-[tool.linter]
+[tool.ruff]
 line-length = 88
-exclude = [
-    "Lib/ctypes/test/test_numbers.py",
-    "Lib/dataclasses.py",
+extend-exclude = [
     "Lib/lib2to3/tests/data/bom.py",
     "Lib/lib2to3/tests/data/crlf.py",
     "Lib/lib2to3/tests/data/different_encoding.py",
     "Lib/lib2to3/tests/data/false_encoding.py",
     "Lib/lib2to3/tests/data/py2_test_grammar.py",
-    "Lib/sqlite3/test/factory.py",
-    "Lib/sqlite3/test/hooks.py",
-    "Lib/sqlite3/test/regression.py",
-    "Lib/sqlite3/test/transactions.py",
-    "Lib/sqlite3/test/types.py",
     "Lib/test/bad_coding2.py",
     "Lib/test/badsyntax_3131.py",
     "Lib/test/badsyntax_pep3120.py",
     "Lib/test/encoded_modules/module_iso_8859_1.py",
     "Lib/test/encoded_modules/module_koi8_r.py",
-    "Lib/test/sortperf.py",
-    "Lib/test/test_email/torture_test.py",
     "Lib/test/test_fstring.py",
-    "Lib/test/test_genericpath.py",
-    "Lib/test/test_getopt.py",
     "Lib/test/test_grammar.py",
-    "Lib/test/test_htmlparser.py",
-    "Lib/test/test_importlib/stubs.py",
-    "Lib/test/test_importlib/test_files.py",
-    "Lib/test/test_importlib/test_metadata_api.py",
-    "Lib/test/test_importlib/test_open.py",
     "Lib/test/test_importlib/test_util.py",
     "Lib/test/test_named_expressions.py",
     "Lib/test/test_patma.py",
-    "Lib/test/test_peg_generator/__main__.py",
-    "Lib/test/test_pipes.py",
     "Lib/test/test_source_encoding.py",
-    "Lib/test/test_weakref.py",
-    "Lib/test/test_webbrowser.py",
-    "Lib/tkinter/__main__.py",
-    "Lib/tkinter/test/test_tkinter/test_variables.py",
-    "Modules/_decimal/libmpdec/literature/fnt.py",
-    "Modules/_decimal/tests/deccheck.py",
     "Tools/c-analyzer/c_parser/parser/_delim.py",
     "Tools/i18n/pygettext.py",
     "Tools/test2to3/maintest.py",
@@ -185,17 +275,21 @@ Next, to benchmark the release build:
 ```shell
 cargo build --release
 
-hyperfine --ignore-failure --warmup 1 \
+hyperfine --ignore-failure --warmup 10 --runs 100 \
   "./target/release/ruff ./resources/test/cpython/ --no-cache" \
   "./target/release/ruff ./resources/test/cpython/"
 
 Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
-  Time (mean ± σ):     353.6 ms ±   7.6 ms    [User: 2868.8 ms, System: 171.5 ms]
-  Range (min … max):   344.4 ms … 367.3 ms    10 runs
+  Time (mean ± σ):     297.4 ms ±   4.9 ms    [User: 2460.0 ms, System: 67.2 ms]
+  Range (min … max):   287.7 ms … 312.1 ms    100 runs
+
+  Warning: Ignoring non-zero exit code.
 
 Benchmark 2: ./target/release/ruff ./resources/test/cpython/
-  Time (mean ± σ):      59.6 ms ±   2.5 ms    [User: 36.4 ms, System: 345.6 ms]
-  Range (min … max):    55.9 ms …  67.0 ms    48 runs
+  Time (mean ± σ):      79.6 ms ±   7.3 ms    [User: 59.7 ms, System: 356.1 ms]
+  Range (min … max):    62.4 ms … 111.2 ms    100 runs
+
+  Warning: Ignoring non-zero exit code.
 ```
 
 To benchmark against the ecosystem's existing tools:
@@ -207,79 +301,69 @@ hyperfine --ignore-failure --warmup 5 \
   "pyflakes resources/test/cpython" \
   "autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython" \
   "pycodestyle resources/test/cpython" \
-  "pycodestyle --select E501 resources/test/cpython" \
   "flake8 resources/test/cpython" \
-  "flake8 --select=F831,F541,F634,F403,F706,F901,E501 resources/test/cpython" \
-  "python -m scripts.run_flake8 resources/test/cpython" \
-  "python -m scripts.run_flake8 resources/test/cpython --select=F831,F541,F634,F403,F706,F901,E501"
+  "python -m scripts.run_flake8 resources/test/cpython"
 ```
 
 In order, these evaluate:
+
 - ruff
 - Pylint
 - PyFlakes
 - autoflake
 - pycodestyle
-- pycodestyle, limited to the checks supported by ruff
 - Flake8
-- Flake8, limited to the checks supported by ruff
 - Flake8, with a hack to enable multiprocessing on macOS
-- Flake8, with a hack to enable multiprocessing on macOS, limited to the checks supported by ruff
 
 (You can `poetry install` from `./scripts` to create a working environment for the above.)
 
 ```shell
 Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
-  Time (mean ± σ):     469.3 ms ±  16.3 ms    [User: 2663.0 ms, System: 972.5 ms]
-  Range (min … max):   445.2 ms … 494.8 ms    10 runs
+  Time (mean ± σ):     297.9 ms ±   7.0 ms    [User: 2436.6 ms, System: 65.9 ms]
+  Range (min … max):   289.9 ms … 314.6 ms    10 runs
+
+  Warning: Ignoring non-zero exit code.
 
 Benchmark 2: pylint --recursive=y resources/test/cpython/
-  Time (mean ± σ):     27.211 s ±  0.097 s    [User: 26.405 s, System: 0.799 s]
-  Range (min … max):   27.056 s … 27.349 s    10 runs
+  Time (mean ± σ):     37.634 s ±  0.225 s    [User: 36.728 s, System: 0.853 s]
+  Range (min … max):   37.201 s … 38.106 s    10 runs
+
+  Warning: Ignoring non-zero exit code.
 
 Benchmark 3: pyflakes resources/test/cpython
-  Time (mean ± σ):     27.309 s ±  0.033 s    [User: 27.137 s, System: 0.169 s]
-  Range (min … max):   27.267 s … 27.372 s    10 runs
+  Time (mean ± σ):     40.950 s ±  0.449 s    [User: 40.688 s, System: 0.229 s]
+  Range (min … max):   40.348 s … 41.671 s    10 runs
+
+  Warning: Ignoring non-zero exit code.
 
 Benchmark 4: autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython
-  Time (mean ± σ):      8.027 s ±  0.024 s    [User: 74.255 s, System: 0.953 s]
-  Range (min … max):    7.969 s …  8.052 s    10 runs
+  Time (mean ± σ):     11.562 s ±  0.160 s    [User: 107.022 s, System: 1.143 s]
+  Range (min … max):   11.417 s … 11.917 s    10 runs
 
 Benchmark 5: pycodestyle resources/test/cpython
-  Time (mean ± σ):     41.666 s ±  0.266 s    [User: 41.531 s, System: 0.132 s]
-  Range (min … max):   41.295 s … 41.980 s    10 runs
+  Time (mean ± σ):     67.428 s ±  0.985 s    [User: 67.199 s, System: 0.203 s]
+  Range (min … max):   65.313 s … 68.496 s    10 runs
 
-Benchmark 6: pycodestyle --select E501 resources/test/cpython
-  Time (mean ± σ):     14.547 s ±  0.077 s    [User: 14.466 s, System: 0.079 s]
-  Range (min … max):   14.429 s … 14.695 s    10 runs
+  Warning: Ignoring non-zero exit code.
 
-Benchmark 7: flake8 resources/test/cpython
-  Time (mean ± σ):     75.700 s ±  0.152 s    [User: 75.254 s, System: 0.440 s]
-  Range (min … max):   75.513 s … 76.014 s    10 runs
+Benchmark 6: flake8 resources/test/cpython
+  Time (mean ± σ):     116.099 s ±  1.178 s    [User: 115.217 s, System: 0.845 s]
+  Range (min … max):   114.180 s … 117.724 s    10 runs
 
-Benchmark 8: flake8 --select=F831,F541,F634,F403,F706,F901,E501 resources/test/cpython
-  Time (mean ± σ):     75.122 s ±  0.532 s    [User: 74.677 s, System: 0.440 s]
-  Range (min … max):   74.130 s … 75.606 s    10 runs
+  Warning: Ignoring non-zero exit code.
 
-Benchmark 9: python -m scripts.run_flake8 resources/test/cpython
-  Time (mean ± σ):     12.794 s ±  0.147 s    [User: 90.792 s, System: 0.738 s]
-  Range (min … max):   12.606 s … 13.030 s    10 runs
-
-Benchmark 10: python -m scripts.run_flake8 resources/test/cpython --select=F831,F541,F634,F403,F706,F901,E501
-  Time (mean ± σ):     12.487 s ±  0.118 s    [User: 90.052 s, System: 0.714 s]
-  Range (min … max):   12.265 s … 12.665 s    10 runs
+Benchmark 7: python -m scripts.run_flake8 resources/test/cpython
+  Time (mean ± σ):     20.477 s ±  0.349 s    [User: 142.372 s, System: 1.504 s]
+  Range (min … max):   20.107 s … 21.183 s    10 runs
 
 Summary
   './target/release/ruff ./resources/test/cpython/ --no-cache' ran
-   17.10 ± 0.60 times faster than 'autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython'
-   26.60 ± 0.96 times faster than 'python -m scripts.run_flake8 resources/test/cpython --select=F831,F541,F634,F403,F706,F901,E501'
-   27.26 ± 1.00 times faster than 'python -m scripts.run_flake8 resources/test/cpython'
-   30.99 ± 1.09 times faster than 'pycodestyle --select E501 resources/test/cpython'
-   57.98 ± 2.03 times faster than 'pylint --recursive=y resources/test/cpython/'
-   58.19 ± 2.02 times faster than 'pyflakes resources/test/cpython'
-   88.77 ± 3.14 times faster than 'pycodestyle resources/test/cpython'
-  160.06 ± 5.68 times faster than 'flake8 --select=F831,F541,F634,F403,F706,F901,E501 resources/test/cpython'
-  161.29 ± 5.61 times faster than 'flake8 resources/test/cpython'
+   38.81 ± 1.05 times faster than 'autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython'
+   68.74 ± 1.99 times faster than 'python -m scripts.run_flake8 resources/test/cpython'
+  126.33 ± 3.05 times faster than 'pylint --recursive=y resources/test/cpython/'
+  137.46 ± 3.55 times faster than 'pyflakes resources/test/cpython'
+  226.35 ± 6.23 times faster than 'pycodestyle resources/test/cpython'
+  389.73 ± 9.92 times faster than 'flake8 resources/test/cpython'
 ```
 
 ## License

demo/.gitignore

@@ -0,0 +1,24 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?

demo/.prettierignore

@@ -0,0 +1,2 @@
+dist
+node_modules

demo/index.css

@@ -0,0 +1,7 @@
+body,
+html,
+#root {
+  margin: 0;
+  width: 100%;
+  height: 100%;
+}

demo/index.html

@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <meta
+      name="description"
+      content="An in-browser playground for Ruff, an extremely fast Python linter written in Rust."
+    />
+    <meta name="keywords" content="ruff, python, rust, webassembly, wasm" />
+    <title>Ruff Playground</title>
+    <link
+      rel="icon"
+      href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🛠️</text></svg>"
+    />
+  </head>
+  <body>
+    <div id="root"></div>
+    <div style="display: flex; position: fixed; right: 16px; top: 16px">
+      <a href="https://GitHub.com/charliermarsh/ruff"
+        ><img
+          src="https://img.shields.io/github/stars/charliermarsh/ruff.svg?style=social&label=GitHub&maxAge=2592000&?logoWidth=100"
+          alt="GitHub stars"
+          style="width: 120px"
+      /></a>
+    </div>
+    <script type="module" src="/src/main.tsx"></script>
+  </body>
+</html>

demo/package.json

@@ -0,0 +1,26 @@
+{
+  "name": "demo",
+  "private": true,
+  "version": "0.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "tsc && vite build",
+    "preview": "vite preview",
+    "push": "wrangler pages publish dist --project-name=ruff"
+  },
+  "dependencies": {
+    "@monaco-editor/react": "^4.4.5",
+    "monaco-editor": "^0.34.0",
+    "prettier": "^2.7.1",
+    "react": "^18.2.0",
+    "react-dom": "^18.2.0"
+  },
+  "devDependencies": {
+    "@types/react": "^18.0.17",
+    "@types/react-dom": "^18.0.6",
+    "@vitejs/plugin-react": "^2.1.0",
+    "typescript": "^4.6.4",
+    "vite": "^3.1.0"
+  }
+}

demo/public/vite.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--logos" width="31.88" height="32" preserveAspectRatio="xMidYMid meet" viewBox="0 0 256 257"><defs><linearGradient id="IconifyId1813088fe1fbc01fb466" x1="-.828%" x2="57.636%" y1="7.652%" y2="78.411%"><stop offset="0%" stop-color="#41D1FF"></stop><stop offset="100%" stop-color="#BD34FE"></stop></linearGradient><linearGradient id="IconifyId1813088fe1fbc01fb467" x1="43.376%" x2="50.316%" y1="2.242%" y2="89.03%"><stop offset="0%" stop-color="#FFEA83"></stop><stop offset="8.333%" stop-color="#FFDD35"></stop><stop offset="100%" stop-color="#FFA800"></stop></linearGradient></defs><path fill="url(#IconifyId1813088fe1fbc01fb466)" d="M255.153 37.938L134.897 252.976c-2.483 4.44-8.862 4.466-11.382.048L.875 37.958c-2.746-4.814 1.371-10.646 6.827-9.67l120.385 21.517a6.537 6.537 0 0 0 2.322-.004l117.867-21.483c5.438-.991 9.574 4.796 6.877 9.62Z"></path><path fill="url(#IconifyId1813088fe1fbc01fb467)" d="M185.432.063L96.44 17.501a3.268 3.268 0 0 0-2.634 3.014l-5.474 92.456a3.268 3.268 0 0 0 3.997 3.378l24.777-5.718c2.318-.535 4.413 1.507 3.936 3.838l-7.361 36.047c-.495 2.426 1.782 4.5 4.151 3.78l15.304-4.649c2.372-.72 4.652 1.36 4.15 3.788l-11.698 56.621c-.732 3.542 3.979 5.473 5.943 2.437l1.313-2.028l72.516-144.72c1.215-2.423-.88-5.186-3.54-4.672l-25.505 4.922c-2.396.462-4.435-1.77-3.759-4.114l16.646-57.705c.677-2.35-1.37-4.583-3.769-4.113Z"></path></svg>

demo/src/App.tsx

@@ -0,0 +1,69 @@
+import Editor, { Monaco } from "@monaco-editor/react";
+import { editor, MarkerSeverity } from "monaco-editor/esm/vs/editor/editor.api";
+import React, { useCallback, useEffect, useState } from "react";
+import { DEFAULT_SOURCE } from "./constants";
+import init, { check } from "./pkg/ruff.js";
+import { Check } from "./types";
+import IStandaloneCodeEditor = editor.IStandaloneCodeEditor;
+
+function App() {
+  const [initialized, setInitialized] = useState<boolean>(false);
+  const [_, setCounter] = useState(0);
+  const [monaco, setMonaco] = useState<Monaco | null>(null);
+
+  // Load the WASM module.
+  useEffect(() => {
+    init().then(() => setInitialized(true));
+  }, []);
+
+  const handleEditorChange = useCallback(
+    () => setCounter((counter) => counter + 1),
+    []
+  );
+  const handleEditorDidMount = useCallback(
+    (editor: IStandaloneCodeEditor, monaco: Monaco) => {
+      setMonaco(monaco);
+    },
+    []
+  );
+
+  if (initialized) {
+    if (monaco) {
+      const editor = monaco.editor;
+      if (editor) {
+        const model = editor.getModels()[0];
+        if (model) {
+          const checks: Check[] = JSON.parse(check(model.getValue()));
+          editor.setModelMarkers(
+            model,
+            "owner",
+            checks.map((check) => ({
+              startLineNumber: check.location.row,
+              startColumn: check.location.column,
+              endLineNumber: check.location.row,
+              endColumn: check.location.column,
+              message: `${check.code}: ${check.message}`,
+              severity: MarkerSeverity.Error,
+            }))
+          );
+        }
+      }
+    }
+  }
+
+  return (
+    <Editor
+      height={"100%"}
+      width={"100%"}
+      path={"ruff"}
+      options={{ readOnly: false, minimap: { enabled: false } }}
+      defaultLanguage="python"
+      defaultValue={DEFAULT_SOURCE}
+      theme={"light"}
+      onMount={handleEditorDidMount}
+      onChange={handleEditorChange}
+    />
+  );
+}
+
+export default App;

demo/src/assets/react.svg

@@ -0,0 +1,2 @@
+<svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" class="iconify iconify--logos"
+  width="35.93" height="32" preserveAspectRatio="xMidYMid meet" viewBox="0 0 256 228"><path fill="#00D8FF" d="M210.483 73.824a171.49 171.49 0 0 0-8.24-2.597c.465-1.9.893-3.777 1.273-5.621c6.238-30.281 2.16-54.676-11.769-62.708c-13.355-7.7-35.196.329-57.254 19.526a171.23 171.23 0 0 0-6.375 5.848a155.866 155.866 0 0 0-4.241-3.917C100.759 3.829 77.587-4.822 63.673 3.233C50.33 10.957 46.379 33.89 51.995 62.588a170.974 170.974 0 0 0 1.892 8.48c-3.28.932-6.445 1.924-9.474 2.98C17.309 83.498 0 98.307 0 113.668c0 15.865 18.582 31.778 46.812 41.427a145.52 145.52 0 0 0 6.921 2.165a167.467 167.467 0 0 0-2.01 9.138c-5.354 28.2-1.173 50.591 12.134 58.266c13.744 7.926 36.812-.22 59.273-19.855a145.567 145.567 0 0 0 5.342-4.923a168.064 168.064 0 0 0 6.92 6.314c21.758 18.722 43.246 26.282 56.54 18.586c13.731-7.949 18.194-32.003 12.4-61.268a145.016 145.016 0 0 0-1.535-6.842c1.62-.48 3.21-.974 4.76-1.488c29.348-9.723 48.443-25.443 48.443-41.52c0-15.417-17.868-30.326-45.517-39.844Zm-6.365 70.984c-1.4.463-2.836.91-4.3 1.345c-3.24-10.257-7.612-21.163-12.963-32.432c5.106-11 9.31-21.767 12.459-31.957c2.619.758 5.16 1.557 7.61 2.4c23.69 8.156 38.14 20.213 38.14 29.504c0 9.896-15.606 22.743-40.946 31.14Zm-10.514 20.834c2.562 12.94 2.927 24.64 1.23 33.787c-1.524 8.219-4.59 13.698-8.382 15.893c-8.067 4.67-25.32-1.4-43.927-17.412a156.726 156.726 0 0 1-6.437-5.87c7.214-7.889 14.423-17.06 21.459-27.246c12.376-1.098 24.068-2.894 34.671-5.345a134.17 134.17 0 0 1 1.386 6.193ZM87.276 214.515c-7.882 2.783-14.16 2.863-17.955.675c-8.075-4.657-11.432-22.636-6.853-46.752a156.923 156.923 0 0 1 1.869-8.499c10.486 2.32 22.093 3.988 34.498 4.994c7.084 9.967 14.501 19.128 21.976 27.15a134.668 134.668 0 0 1-4.877 4.492c-9.933 8.682-19.886 14.842-28.658 17.94ZM50.35 144.747c-12.483-4.267-22.792-9.812-29.858-15.863c-6.35-5.437-9.555-10.836-9.555-15.216c0-9.322 13.897-21.212 37.076-29.293c2.813-.98 5.757-1.905 8.812-2.773c3.204 10.42 7.406 21.315 12.477 32.332c-5.137 11.18-9.399 22.249-12.634 32.792a134.718 134.718 0 0 1-6.318-1.979Zm12.378-84.26c-4.811-24.587-1.616-43.134 6.425-47.789c8.564-4.958 27.502 2.111 47.463 19.835a144.318 144.318 0 0 1 3.841 3.545c-7.438 7.987-14.787 17.08-21.808 26.988c-12.04 1.116-23.565 2.908-34.161 5.309a160.342 160.342 0 0 1-1.76-7.887Zm110.427 27.268a347.8 347.8 0 0 0-7.785-12.803c8.168 1.033 15.994 2.404 23.343 4.08c-2.206 7.072-4.956 14.465-8.193 22.045a381.151 381.151 0 0 0-7.365-13.322Zm-45.032-43.861c5.044 5.465 10.096 11.566 15.065 18.186a322.04 322.04 0 0 0-30.257-.006c4.974-6.559 10.069-12.652 15.192-18.18ZM82.802 87.83a323.167 323.167 0 0 0-7.227 13.238c-3.184-7.553-5.909-14.98-8.134-22.152c7.304-1.634 15.093-2.97 23.209-3.984a321.524 321.524 0 0 0-7.848 12.897Zm8.081 65.352c-8.385-.936-16.291-2.203-23.593-3.793c2.26-7.3 5.045-14.885 8.298-22.6a321.187 321.187 0 0 0 7.257 13.246c2.594 4.48 5.28 8.868 8.038 13.147Zm37.542 31.03c-5.184-5.592-10.354-11.779-15.403-18.433c4.902.192 9.899.29 14.978.29c5.218 0 10.376-.117 15.453-.343c-4.985 6.774-10.018 12.97-15.028 18.486Zm52.198-57.817c3.422 7.8 6.306 15.345 8.596 22.52c-7.422 1.694-15.436 3.058-23.88 4.071a382.417 382.417 0 0 0 7.859-13.026a347.403 347.403 0 0 0 7.425-13.565Zm-16.898 8.101a358.557 358.557 0 0 1-12.281 19.815a329.4 329.4 0 0 1-23.444.823c-7.967 0-15.716-.248-23.178-.732a310.202 310.202 0 0 1-12.513-19.846h.001a307.41 307.41 0 0 1-10.923-20.627a310.278 310.278 0 0 1 10.89-20.637l-.001.001a307.318 307.318 0 0 1 12.413-19.761c7.613-.576 15.42-.876 23.31-.876H128c7.926 0 15.743.303 23.354.883a329.357 329.357 0 0 1 12.335 19.695a358.489 358.489 0 0 1 11.036 20.54a329.472 329.472 0 0 1-11 20.722Zm22.56-122.124c8.572 4.944 11.906 24.881 6.52 51.026c-.344 1.668-.73 3.367-1.15 5.09c-10.622-2.452-22.155-4.275-34.23-5.408c-7.034-10.017-14.323-19.124-21.64-27.008a160.789 160.789 0 0 1 5.888-5.4c18.9-16.447 36.564-22.941 44.612-18.3ZM128 90.808c12.625 0 22.86 10.235 22.86 22.86s-10.235 22.86-22.86 22.86s-22.86-10.235-22.86-22.86s10.235-22.86 22.86-22.86Z"></path></svg>

demo/src/constants.ts

@@ -0,0 +1,55 @@
+export const DEFAULT_SOURCE = `#: E721
+if type(res) == type(42):
+    pass
+#: E721
+if type(res) != type(""):
+    pass
+#: E721
+import types
+
+if res == types.IntType:
+    pass
+#: E721
+import types
+
+if type(res) is not types.ListType:
+    pass
+#: E721
+assert type(res) == type(False) or type(res) == type(None)
+#: E721
+assert type(res) == type([])
+#: E721
+assert type(res) == type(())
+#: E721
+assert type(res) == type((0,))
+#: E721
+assert type(res) == type((0))
+#: E721
+assert type(res) != type((1,))
+#: E721
+assert type(res) is type((1,))
+#: E721
+assert type(res) is not type((1,))
+#: E721
+assert type(res) == type(
+    [
+        2,
+    ]
+)
+#: E721
+assert type(res) == type(())
+#: E721
+assert type(res) == type((0,))
+
+#: Okay
+import types
+
+if isinstance(res, int):
+    pass
+if isinstance(res, str):
+    pass
+if isinstance(res, types.MethodType):
+    pass
+if type(a) != type(b) or type(a) == type(ccc):
+    pass
+`;

demo/src/main.tsx

@@ -0,0 +1,10 @@
+import React from "react";
+import ReactDOM from "react-dom/client";
+import App from "./App";
+import "../index.css";
+
+ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+);

demo/src/types.ts

@@ -0,0 +1,5 @@
+export type Check = {
+  code: string;
+  message: string;
+  location: { row: number; column: number };
+};

demo/src/vite-env.d.ts

@@ -0,0 +1 @@
+/// <reference types="vite/client" />

demo/tsconfig.json

@@ -0,0 +1,21 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "useDefineForClassFields": true,
+    "lib": ["DOM", "DOM.Iterable", "ESNext"],
+    "allowJs": false,
+    "skipLibCheck": true,
+    "esModuleInterop": false,
+    "allowSyntheticDefaultImports": true,
+    "strict": true,
+    "forceConsistentCasingInFileNames": true,
+    "module": "ESNext",
+    "moduleResolution": "Node",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "jsx": "react-jsx"
+  },
+  "include": ["src"],
+  "references": [{ "path": "./tsconfig.node.json" }]
+}

demo/tsconfig.node.json

@@ -0,0 +1,9 @@
+{
+  "compilerOptions": {
+    "composite": true,
+    "module": "ESNext",
+    "moduleResolution": "Node",
+    "allowSyntheticDefaultImports": true
+  },
+  "include": ["vite.config.ts"]
+}

demo/vite.config.ts

@@ -0,0 +1,7 @@
+import { defineConfig } from "vite";
+import react from "@vitejs/plugin-react";
+
+// https://vitejs.dev/config/
+export default defineConfig({
+  plugins: [react()],
+});

examples/generate_rules_table.rs

@@ -0,0 +1,19 @@
+/// Generate a Markdown-compatible table of supported lint rules.
+use ruff::checks::{CheckCode, ALL_CHECK_CODES};
+
+fn main() {
+    let mut check_codes: Vec<CheckCode> = ALL_CHECK_CODES.to_vec();
+    check_codes.sort();
+
+    println!("| Code | Name | Message |");
+    println!("| ---- | ----- | ------- |");
+    for check_code in check_codes {
+        let check_kind = check_code.kind();
+        println!(
+            "| {} | {} | {} |",
+            check_kind.code().as_str(),
+            check_kind.name(),
+            check_kind.body()
+        );
+    }
+}

examples/print_ast.rs

@@ -0,0 +1,25 @@
+/// Print the AST for a given Python file.
+use std::path::PathBuf;
+
+use anyhow::Result;
+use clap::{Parser, ValueHint};
+use rustpython_parser::parser;
+
+use ruff::fs;
+
+#[derive(Debug, Parser)]
+struct Cli {
+    #[clap(parse(from_os_str), value_hint = ValueHint::FilePath, required = true)]
+    file: PathBuf,
+}
+
+fn main() -> Result<()> {
+    let cli = Cli::parse();
+
+    let contents = fs::read_file(&cli.file)?;
+    let python_ast = parser::parse_program(&contents, &cli.file.to_string_lossy())?;
+
+    println!("{:#?}", python_ast);
+
+    Ok(())
+}

examples/print_tokens.rs

@@ -0,0 +1,25 @@
+/// Print the token stream for a given Python file.
+use std::path::PathBuf;
+
+use anyhow::Result;
+use clap::{Parser, ValueHint};
+use rustpython_parser::lexer;
+
+use ruff::fs;
+
+#[derive(Debug, Parser)]
+struct Cli {
+    #[clap(parse(from_os_str), value_hint = ValueHint::FilePath, required = true)]
+    file: PathBuf,
+}
+
+fn main() -> Result<()> {
+    let cli = Cli::parse();
+
+    let contents = fs::read_file(&cli.file)?;
+    for (_, tok, _) in lexer::make_tokenizer(&contents).flatten() {
+        println!("{:#?}", tok);
+    }
+
+    Ok(())
+}

index.html

@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<html lang="en-US">
+<head>
+  <meta charset="utf-8"/>
+  <title>hello-wasm example</title>
+</head>
+<body>
+<script type="module">
+  import init, {check} from "./pkg/ruff.js";
+
+  init().then(() => {
+    console.log(check("if (1, 2): pass"));
+  });
+</script>
+</body>
+</html>

pyproject.toml

@@ -19,10 +19,12 @@ classifiers = [
 ]
 author = "Charlie Marsh"
 author_email = "charlie.r.marsh@gmail.com"
-url = "https://github.com/charliermarsh/ruff"
 description = "An extremely fast Python linter, written in Rust."
 requires-python = ">=3.7"
 
+[project.urls]
+repository = "https://github.com/charliermarsh/ruff"
+
 [build-system]
 requires = ["maturin>=0.13,<0.14"]
 build-backend = "maturin"

resources/test/fixtures/E402.py

@@ -0,0 +1,28 @@
+"""Top-level docstring."""
+import a
+
+try:
+    import b
+except ImportError:
+    pass
+else:
+    pass
+
+import c
+
+if x > 0:
+    import d
+else:
+    import e
+
+y = x + 1
+
+import f
+
+
+def foo() -> None:
+    import e
+
+
+if __name__ == "__main__":
+    import g

resources/test/fixtures/E501.py

@@ -4,3 +4,6 @@
 
 Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
 """
+
+_ = "---------------------------------------------------------------------------AAAAAAA"
+_ = "---------------------------------------------------------------------------亜亜亜亜亜亜亜"

resources/test/fixtures/E711.py

@@ -0,0 +1,50 @@
+#: E711
+if res == None:
+    pass
+#: E711
+if res != None:
+    pass
+#: E711
+if None == res:
+    pass
+#: E711
+if None != res:
+    pass
+#: E711
+if res[1] == None:
+    pass
+#: E711
+if res[1] != None:
+    pass
+#: E711
+if None != res[1]:
+    pass
+#: E711
+if None == res[1]:
+    pass
+
+#: Okay
+if x not in y:
+    pass
+
+if not (X in Y or X is Z):
+    pass
+
+if not (X in Y):
+    pass
+
+if x is not y:
+    pass
+
+if X is not Y is not Z:
+    pass
+
+if TrueElement.get_element(True) == TrueElement.get_element(False):
+    pass
+
+if (True) == TrueElement or x == TrueElement:
+    pass
+
+assert (not foo) in bar
+assert {"x": not foo} in bar
+assert [42, not foo] in bar

resources/test/fixtures/E712.py

@@ -0,0 +1,46 @@
+#: E712
+if res == True:
+    pass
+#: E712
+if res != False:
+    pass
+#: E712
+if True != res:
+    pass
+#: E712
+if False == res:
+    pass
+#: E712
+if res[1] == True:
+    pass
+#: E712
+if res[1] != False:
+    pass
+#: E712
+var = 1 if cond == True else -1 if cond == False else cond
+#: E712
+if (True) == TrueElement or x == TrueElement:
+    pass
+
+#: Okay
+if x not in y:
+    pass
+
+if not (X in Y or X is Z):
+    pass
+
+if not (X in Y):
+    pass
+
+if x is not y:
+    pass
+
+if X is not Y is not Z:
+    pass
+
+if TrueElement.get_element(True) == TrueElement.get_element(False):
+    pass
+
+assert (not foo) in bar
+assert {"x": not foo} in bar
+assert [42, not foo] in bar

resources/test/fixtures/E713.py

@@ -0,0 +1,38 @@
+#: E713
+if not X in Y:
+    pass
+#: E713
+if not X.B in Y:
+    pass
+#: E713
+if not X in Y and Z == "zero":
+    pass
+#: E713
+if X == "zero" or not Y in Z:
+    pass
+#: E713
+if not (X in Y):
+    pass
+
+#: Okay
+if x not in y:
+    pass
+
+if not (X in Y or X is Z):
+    pass
+
+if x is not y:
+    pass
+
+if X is not Y is not Z:
+    pass
+
+if TrueElement.get_element(True) == TrueElement.get_element(False):
+    pass
+
+if (True) == TrueElement or x == TrueElement:
+    pass
+
+assert (not foo) in bar
+assert {"x": not foo} in bar
+assert [42, not foo] in bar

resources/test/fixtures/E714.py

@@ -0,0 +1,38 @@
+#: E714
+if not X is Y:
+    pass
+#: E714
+if not X.B is Y:
+    pass
+#: E714
+if not X is Y is not Z:
+    pass
+
+#: Okay
+if not X is not Y:
+    pass
+
+if x not in y:
+    pass
+
+if not (X in Y or X is Z):
+    pass
+
+if not (X in Y):
+    pass
+
+if x is not y:
+    pass
+
+if X is not Y is not Z:
+    pass
+
+if TrueElement.get_element(True) == TrueElement.get_element(False):
+    pass
+
+if (True) == TrueElement or x == TrueElement:
+    pass
+
+assert (not foo) in bar
+assert {"x": not foo} in bar
+assert [42, not foo] in bar

resources/test/fixtures/E721.py

@@ -0,0 +1,54 @@
+#: E721
+if type(res) == type(42):
+    pass
+#: E721
+if type(res) != type(""):
+    pass
+#: E721
+import types
+
+if res == types.IntType:
+    pass
+#: E721
+import types
+
+if type(res) is not types.ListType:
+    pass
+#: E721
+assert type(res) == type(False) or type(res) == type(None)
+#: E721
+assert type(res) == type([])
+#: E721
+assert type(res) == type(())
+#: E721
+assert type(res) == type((0,))
+#: E721
+assert type(res) == type((0))
+#: E721
+assert type(res) != type((1,))
+#: E721
+assert type(res) is type((1,))
+#: E721
+assert type(res) is not type((1,))
+#: E211 E721
+assert type(res) == type(
+    [
+        2,
+    ]
+)
+#: E201 E201 E202 E721
+assert type(res) == type(())
+#: E201 E202 E721
+assert type(res) == type((0,))
+
+#: Okay
+import types
+
+if isinstance(res, int):
+    pass
+if isinstance(res, str):
+    pass
+if isinstance(res, types.MethodType):
+    pass
+if type(a) != type(b) or type(a) == type(ccc):
+    pass

resources/test/fixtures/E722.py

@@ -0,0 +1,33 @@
+#: E722
+try:
+    pass
+except:
+    pass
+#: E722
+try:
+    pass
+except Exception:
+    pass
+except:
+    pass
+#: E722
+try:
+    pass
+except:
+    pass
+#: Okay
+fake_code = """"
+try:
+    do_something()
+except:
+    pass
+"""
+try:
+    pass
+except Exception:
+    pass
+#: Okay
+from . import compute_type
+
+if compute_type(foo) == 5:
+    pass

resources/test/fixtures/E731.py

@@ -0,0 +1,21 @@
+#: E731
+f = lambda x: 2 * x
+#: E731
+f = lambda x: 2 * x
+#: E731
+while False:
+    this = lambda y, z: 2 * x
+
+
+f = object()
+#: E731
+f.method = lambda: "Method"
+
+f = {}
+#: E731
+f["a"] = lambda x: x ** 2
+
+f = []
+f.append(lambda x: x ** 2)
+
+lambda: "no-op"

resources/test/fixtures/E741.py

@@ -0,0 +1,75 @@
+from contextlib import contextmanager
+
+l = 0
+I = 0
+O = 0
+l: int = 0
+
+a, l = 0, 1
+[a, l] = 0, 1
+a, *l = 0, 1, 2
+a = l = 0
+
+o = 0
+i = 0
+
+for l in range(3):
+    pass
+
+
+for a, l in zip(range(3), range(3)):
+    pass
+
+
+def f1():
+    global l
+    l = 0
+
+
+def f2():
+    l = 0
+
+    def f3():
+        nonlocal l
+        l = 1
+
+    f3()
+    return l
+
+
+def f4(l, /, I):
+    return l, I, O
+
+
+def f5(l=0, *, I=1):
+    return l, I
+
+
+def f6(*l, **I):
+    return l, I
+
+
+@contextmanager
+def ctx1():
+    yield 0
+
+
+with ctx1() as l:
+    pass
+
+
+@contextmanager
+def ctx2():
+    yield 0, 1
+
+
+with ctx2() as (a, l):
+    pass
+
+try:
+    pass
+except ValueError as l:
+    pass
+
+if (l := 5) > 0:
+    pass

resources/test/fixtures/E742.py

@@ -0,0 +1,14 @@
+class l:
+    pass
+
+
+class I:
+    pass
+
+
+class O:
+    pass
+
+
+class X:
+    pass

resources/test/fixtures/E743.py

@@ -0,0 +1,15 @@
+def l():
+    pass
+
+
+def I():
+    pass
+
+
+class X:
+    def O(self):
+        pass
+
+
+def x():
+    pass

resources/test/fixtures/E999.py

@@ -0,0 +1,2 @@
+def x():
+

resources/test/fixtures/F401.py

@@ -0,0 +1,41 @@
+from __future__ import all_feature_names
+import os
+import functools
+from datetime import datetime
+from collections import (
+    Counter,
+    OrderedDict,
+    namedtuple,
+)
+import multiprocessing.pool
+import multiprocessing.process
+import logging.config
+import logging.handlers
+from typing import TYPING_CHECK, NamedTuple, Dict, Type, TypeVar, List, Set, Union, cast
+
+from blah import ClassA, ClassB, ClassC
+
+if TYPING_CHECK:
+    from models import Fruit, Nut, Vegetable
+
+
+class X:
+    datetime: datetime
+    foo: Type["NamedTuple"]
+
+    def a(self) -> "namedtuple":
+        x = os.environ["1"]
+        y = Counter()
+        z = multiprocessing.pool.ThreadPool()
+
+
+__all__ = ["ClassA"] + ["ClassB"]
+__all__ += ["ClassC"]
+
+X = TypeVar("X")
+Y = TypeVar("Y", bound="Dict")
+Z = TypeVar("Z", "List", "Set")
+
+a = list["Fruit"]
+b = Union["Nut", None]
+c = cast("Vegetable", b)

resources/test/fixtures/F402.py

@@ -0,0 +1,9 @@
+import os
+import os.path as path
+
+
+for os in range(3):
+    pass
+
+for path in range(3):
+    pass

resources/test/fixtures/F404.py

@@ -0,0 +1,7 @@
+from __future__ import print_function
+"""Docstring"""
+from __future__ import absolute_import
+
+from collections import namedtuple
+
+from __future__ import print_function

resources/test/fixtures/F405.py

@@ -0,0 +1,11 @@
+from mymodule import *
+
+
+def print_name():
+    print(name)
+
+
+def print_name(name):
+    print(name)
+
+__all__ = ['a']

resources/test/fixtures/F406.py

@@ -0,0 +1,9 @@
+from F634 import *
+
+
+def f():
+    from F634 import *
+
+
+class F:
+    from F634 import *

resources/test/fixtures/F407.py

@@ -0,0 +1,2 @@
+from __future__ import print_function
+from __future__ import non_existent_feature

resources/test/fixtures/F601.py

@@ -0,0 +1,12 @@
+x = {
+    "a": 1,
+    "a": 2,
+    "b": 3,
+    ("a", "b"): 3,
+    ("a", "b"): 4,
+    1.0: 2,
+    1: 0,
+    1: 3,
+    b"123": 1,
+    b"123": 4,
+}

resources/test/fixtures/F602.py

@@ -0,0 +1,7 @@
+a = 1
+b = 2
+x = {
+    a: 1,
+    a: 2,
+    b: 3,
+}

resources/test/fixtures/F622.py

@@ -0,0 +1,3 @@
+*a, *b, c = (1, 2, 3)
+*a, b, c = (1, 2, 3)
+a, b, *c = (1, 2, 3)

resources/test/fixtures/F631.py

@@ -0,0 +1,4 @@
+assert (False, "x")
+assert (False,)
+assert ()
+assert True

resources/test/fixtures/F632.py

@@ -0,0 +1,5 @@
+if x is "abc":
+    pass
+
+if 123 is not y:
+    pass

resources/test/fixtures/F633.py

@@ -0,0 +1,4 @@
+from __future__ import print_function
+import sys
+
+print >> sys.stderr, "Hello"

resources/test/fixtures/F634.py

@@ -6,3 +6,5 @@ for _ in range(5):
         pass
     elif (3, 4):
         pass
+    elif ():
+        pass

resources/test/fixtures/F701.py

@@ -0,0 +1,23 @@
+for i in range(10):
+    break
+else:
+    break
+
+i = 0
+while i < 10:
+    i += 1
+    break
+
+
+def f():
+    for i in range(10):
+        break
+
+    break
+
+
+class Foo:
+    break
+
+
+break

resources/test/fixtures/F702.py

@@ -0,0 +1,23 @@
+for i in range(10):
+    continue
+else:
+    continue
+
+i = 0
+while i < 10:
+    i += 1
+    continue
+
+
+def f():
+    for i in range(10):
+        continue
+
+    continue
+
+
+class Foo:
+    continue
+
+
+continue

resources/test/fixtures/F707.py

@@ -0,0 +1,46 @@
+try:
+    pass
+except:
+    pass
+except ValueError:
+    pass
+
+try:
+    pass
+except:
+    pass
+except ValueError:
+    pass
+finally:
+    pass
+
+try:
+    pass
+except:
+    pass
+except ValueError:
+    pass
+else:
+    pass
+
+try:
+    pass
+except:
+    pass
+
+try:
+    pass
+except ValueError:
+    pass
+except:
+    pass
+
+try:
+    pass
+except ValueError:
+    pass
+
+try:
+    pass
+finally:
+    pass

resources/test/fixtures/F722.py

@@ -0,0 +1,10 @@
+class A:
+    pass
+
+
+def f() -> "A":
+    pass
+
+
+def g() -> "///":
+    pass

resources/test/fixtures/F821.py

@@ -33,14 +33,59 @@ def ternary_optarg(prec, exp_range, itr):
 class Foo:
     CLASS_VAR = 1
     REFERENCES_CLASS_VAR = {"CLASS_VAR": CLASS_VAR}
+    ANNOTATED_CLASS_VAR: int = 2
+
+
+from typing import Literal
 
 
 class Class:
+    copy_on_model_validation: Literal["none", "deep", "shallow"]
+    post_init_call: Literal["before_validation", "after_validation"]
+
     def __init__(self):
-        # TODO(charlie): This should be recognized as a defined variable.
-        Class  # noqa: F821
+        Class
+
 
 try:
     x = 1 / 0
 except Exception as e:
     print(e)
+
+
+y: int = 1
+
+x: "Bar" = 1
+
+[first] = ["yup"]
+
+
+from typing import List, TypedDict
+
+
+class Item(TypedDict):
+    nodes: List[TypedDict("Node", {"name": str})]
+
+
+from enum import Enum
+
+
+class Ticket:
+    class Status(Enum):
+        OPEN = "OPEN"
+        CLOSED = "CLOSED"
+
+    def set_status(self, status: Status):
+        self.status = status
+
+
+def update_tomato():
+    print(TOMATO)
+    TOMATO = "cherry tomato"
+
+
+A = f'{B}'
+A = (
+    f'B'
+    f'{B}'
+)

resources/test/fixtures/F822.py

@@ -0,0 +1,3 @@
+a = 1
+
+__all__ = ["a", "b"]

resources/test/fixtures/F823.py

@@ -15,3 +15,13 @@ def baz():
     global my_var
     global my_dict
     my_dict[my_var] += 1
+
+
+def dec(x):
+    return x
+
+
+@dec
+def f():
+    dec = 1
+    return dec

resources/test/fixtures/F841.py

@@ -14,3 +14,18 @@ def f():
     x = 1
     y = 2
     z = x + y
+
+
+def g():
+    foo = (1, 2)
+    (a, b) = (1, 2)
+
+    bar = (1, 2)
+    (c, d) = bar
+
+    (x, y) = baz = bar
+
+
+def h():
+    locals()
+    x = 1

resources/test/fixtures/R001.py

@@ -0,0 +1,141 @@
+class A:
+    ...
+
+
+class A(object):
+    ...
+
+
+class A(
+    object,
+):
+    ...
+
+
+class A(
+    object,
+    #
+):
+    ...
+
+
+class A(
+    #
+    object,
+):
+    ...
+
+
+class A(
+    #
+    object
+):
+    ...
+
+
+class A(
+    object
+    #
+):
+    ...
+
+
+class A(
+    #
+    object,
+    #
+):
+    ...
+
+
+class A(
+    #
+    object,
+    #
+):
+    ...
+
+
+class A(
+    #
+    object
+    #
+):
+    ...
+
+
+class A(
+    #
+    object
+    #
+):
+    ...
+
+
+class B(A, object):
+    ...
+
+
+class B(object, A):
+    ...
+
+
+class B(
+    object,
+    A,
+):
+    ...
+
+
+class B(
+    A,
+    object,
+):
+    ...
+
+
+class B(
+    object,
+    # Comment on A.
+    A,
+):
+    ...
+
+
+class B(
+    # Comment on A.
+    A,
+    object,
+):
+    ...
+
+
+def f():
+    class A(object):
+        ...
+
+
+class A(
+    object,
+):
+    ...
+
+
+class A(
+    object,  # )
+):
+    ...
+
+
+class A(
+    object  # )
+    ,
+):
+    ...
+
+
+object = A
+
+
+class B(object):
+    ...

resources/test/fixtures/R002.py

@@ -0,0 +1,3 @@
+self.assertEquals (1, 2)
+self.assertEquals(1, 2)
+self.assertEqual(3, 4)

resources/test/fixtures/__init__.py

@@ -0,0 +1,3 @@
+print(__path__)
+
+__all__ = ["a", "b", "c"]

resources/test/fixtures/foo/migrations/migration.py

@@ -0,0 +1,9 @@
+a = "abc"
+b = f"ghi{'jkl'}"
+
+c = f"def"
+d = f"def" + "ghi"
+e = (
+    f"def" +
+    "ghi"
+)

resources/test/fixtures/future_annotations.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from models import Fruit, Nut
+
+
+@dataclass
+class Foo:
+    x: int
+    y: int
+
+    @classmethod
+    def a(cls) -> Foo:
+        return cls(x=0, y=0)
+
+    @classmethod
+    def b(cls) -> "Foo":
+        return cls(x=0, y=0)
+
+    @classmethod
+    def c(cls) -> Bar:
+        return cls(x=0, y=0)
+
+    @classmethod
+    def d(cls) -> Fruit:
+        return cls(x=0, y=0)

resources/test/fixtures/pyproject.toml

@@ -0,0 +1,7 @@
+[tool.ruff]
+line-length = 88
+extend-exclude = [
+    "excluded.py",
+    "migrations",
+    "directory/also_excluded.py",
+]

resources/test/src/F401.py

@@ -1,18 +0,0 @@
-import os
-import functools
-from collections import (
-    Counter,
-    OrderedDict,
-    namedtuple,
-)
-import multiprocessing.pool
-import multiprocessing.process
-import logging.config
-import logging.handlers
-
-
-class X:
-    def a(self) -> "namedtuple":
-        x = os.environ["1"]
-        y = Counter()
-        z = multiprocessing.pool.ThreadPool()

resources/test/src/pyproject.toml

@@ -1,17 +0,0 @@
-[tool.ruff]
-line-length = 88
-exclude = ["excluded.py", "**/migrations"]
-select = [
-    "E501",
-    "F401",
-    "F403",
-    "F541",
-    "F634",
-    "F704",
-    "F706",
-    "F821",
-    "F831",
-    "F832",
-    "F841",
-    "F901",
-]

src/ast.rs

@@ -0,0 +1,5 @@
+pub mod checks;
+pub mod operations;
+pub mod relocate;
+pub mod types;
+pub mod visitor;

src/ast/checks.rs

@@ -0,0 +1,650 @@
+use std::collections::BTreeSet;
+
+use itertools::izip;
+use rustpython_parser::ast::{
+    Arg, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind, Keyword,
+    Location, Stmt, StmtKind, Unaryop,
+};
+
+use crate::ast::operations::SourceCodeLocator;
+use crate::ast::types::{Binding, BindingKind, CheckLocator, FunctionScope, Scope, ScopeKind};
+use crate::autofix::{fixer, fixes};
+use crate::checks::{Check, CheckKind, Fix, RejectedCmpop};
+
+/// Check IfTuple compliance.
+pub fn check_if_tuple(test: &Expr, location: Location) -> 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: Location) -> 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(operand.location),
+                            ));
+                        }
+                    }
+                    Cmpop::Is => {
+                        if check_not_is {
+                            checks.push(Check::new(
+                                CheckKind::NotIsTest,
+                                locator.locate_check(operand.location),
+                            ));
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+
+    checks
+}
+
+/// Check UnusedVariable compliance.
+pub fn check_unused_variables(scope: &Scope, locator: &dyn CheckLocator) -> 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() {
+        // TODO(charlie): Ignore if using `locals`.
+        if binding.used.is_none()
+            && name != "_"
+            && name != "__tracebackhide__"
+            && name != "__traceback_info__"
+            && name != "__traceback_supplement__"
+            && matches!(binding.kind, BindingKind::Assignment)
+        {
+            checks.push(Check::new(
+                CheckKind::UnusedVariable(name.to_string()),
+                locator.locate_check(binding.location),
+            ));
+        }
+    }
+
+    checks
+}
+
+/// Check DoNotAssignLambda compliance.
+pub fn check_do_not_assign_lambda(value: &Expr, location: Location) -> Option<Check> {
+    if let ExprKind::Lambda { .. } = &value.node {
+        Some(Check::new(CheckKind::DoNotAssignLambda, location))
+    } else {
+        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: Location) -> 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: Location) -> 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: Location) -> 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(
+    stmt: &Stmt,
+    name: &str,
+    bases: &[Expr],
+    keywords: &[Keyword],
+    scope: &Scope,
+    locator: &mut SourceCodeLocator,
+    autofix: &fixer::Mode,
+) -> 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,
+                        ..
+                    }) => {
+                        let mut check = Check::new(
+                            CheckKind::UselessObjectInheritance(name.to_string()),
+                            expr.location,
+                        );
+                        if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+                            if let Some(fix) = fixes::remove_class_def_base(
+                                locator,
+                                &stmt.location,
+                                expr.location,
+                                bases,
+                                keywords,
+                            ) {
+                                check.amend(fix);
+                            }
+                        }
+                        return Some(check);
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+
+    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,
+                handler.location,
+            ));
+        }
+    }
+
+    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, expr.location));
+                }
+            }
+        }
+        ExprKind::Name { id, .. } => {
+            if id == "NotImplemented" {
+                return Some(Check::new(CheckKind::RaiseNotImplemented, expr.location));
+            }
+        }
+        _ => {}
+    }
+
+    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, arg.location));
+        }
+        idents.insert(ident);
+    }
+
+    checks
+}
+
+/// Check AssertEquals compliance.
+pub fn check_assert_equals(expr: &Expr, autofix: &fixer::Mode) -> Option<Check> {
+    if let ExprKind::Attribute { value, attr, .. } = &expr.node {
+        if attr == "assertEquals" {
+            if let ExprKind::Name { id, .. } = &value.node {
+                if id == "self" {
+                    let mut check = Check::new(CheckKind::NoAssertEquals, expr.location);
+                    if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+                        check.amend(Fix {
+                            content: "assertEqual".to_string(),
+                            start: Location::new(expr.location.row(), expr.location.column() + 1),
+                            end: Location::new(
+                                expr.location.row(),
+                                expr.location.column() + 1 + "assertEquals".len(),
+                            ),
+                            applied: false,
+                        });
+                    }
+                    return Some(check);
+                }
+            }
+        }
+    }
+    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(k2.location),
+                        ))
+                    }
+                }
+                (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(k2.location),
+                        ))
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+
+    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(comparator.location),
+            ));
+        }
+        if matches!(op, Cmpop::NotEq) {
+            checks.push(Check::new(
+                CheckKind::NoneComparison(RejectedCmpop::NotEq),
+                locator.locate_check(comparator.location),
+            ));
+        }
+    }
+
+    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(comparator.location),
+                ));
+            }
+            if matches!(op, Cmpop::NotEq) {
+                checks.push(Check::new(
+                    CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
+                    locator.locate_check(comparator.location),
+                ));
+            }
+        }
+    }
+
+    // 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(comparator.location),
+                ));
+            }
+            if matches!(op, Cmpop::NotEq) {
+                checks.push(Check::new(
+                    CheckKind::NoneComparison(RejectedCmpop::NotEq),
+                    locator.locate_check(comparator.location),
+                ));
+            }
+        }
+
+        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(comparator.location),
+                    ));
+                }
+                if matches!(op, Cmpop::NotEq) {
+                    checks.push(Check::new(
+                        CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
+                        locator.locate_check(comparator.location),
+                    ));
+                }
+            }
+        }
+    }
+
+    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: Location,
+) -> 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: Location,
+) -> 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: Location,
+) -> 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::TooManyExpressionsInStarredAssignment,
+                    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(stmt.location),
+        ))
+    } 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(stmt.location),
+        ))
+    } else {
+        None
+    }
+}

src/ast/operations.rs

@@ -0,0 +1,150 @@
+use rustpython_parser::ast::{Constant, Expr, ExprKind, Location, Stmt, StmtKind};
+
+use crate::ast::types::{BindingKind, Scope};
+
+/// Extract the names bound to a given __all__ assignment.
+pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
+    let mut names: Vec<String> = vec![];
+
+    fn add_to_names(names: &mut Vec<String>, elts: &[Expr]) {
+        for elt in elts {
+            if let ExprKind::Constant {
+                value: Constant::Str(value),
+                ..
+            } = &elt.node
+            {
+                names.push(value.to_string())
+            }
+        }
+    }
+
+    // Grab the existing bound __all__ values.
+    if let StmtKind::AugAssign { .. } = &stmt.node {
+        if let Some(binding) = scope.values.get("__all__") {
+            if let BindingKind::Export(existing) = &binding.kind {
+                names.extend_from_slice(existing);
+            }
+        }
+    }
+
+    if let Some(value) = match &stmt.node {
+        StmtKind::Assign { value, .. } => Some(value),
+        StmtKind::AnnAssign { value, .. } => value.as_ref(),
+        StmtKind::AugAssign { value, .. } => Some(value),
+        _ => None,
+    } {
+        match &value.node {
+            ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
+                add_to_names(&mut names, elts)
+            }
+            ExprKind::BinOp { left, right, .. } => {
+                let mut current_left = left;
+                let mut current_right = right;
+                while let Some(elts) = match &current_right.node {
+                    ExprKind::List { elts, .. } => Some(elts),
+                    ExprKind::Tuple { elts, .. } => Some(elts),
+                    _ => None,
+                } {
+                    add_to_names(&mut names, elts);
+                    match &current_left.node {
+                        ExprKind::BinOp { left, right, .. } => {
+                            current_left = left;
+                            current_right = right;
+                        }
+                        ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
+                            add_to_names(&mut names, elts);
+                            break;
+                        }
+                        _ => break,
+                    }
+                }
+            }
+            _ => {}
+        }
+    }
+
+    names
+}
+
+/// Check if a node is parent of a conditional branch.
+pub fn on_conditional_branch(parent_stack: &[usize], parents: &[&Stmt]) -> bool {
+    for index in parent_stack.iter().rev() {
+        let parent = parents[*index];
+        if matches!(parent.node, StmtKind::If { .. } | StmtKind::While { .. }) {
+            return true;
+        }
+        if let StmtKind::Expr { value } = &parent.node {
+            if matches!(value.node, ExprKind::IfExp { .. }) {
+                return true;
+            }
+        }
+    }
+
+    false
+}
+
+/// Check if a node is in a nested block.
+pub fn in_nested_block(parent_stack: &[usize], parents: &[&Stmt]) -> bool {
+    for index in parent_stack.iter().rev() {
+        let parent = parents[*index];
+        if matches!(
+            parent.node,
+            StmtKind::Try { .. } | StmtKind::If { .. } | StmtKind::With { .. }
+        ) {
+            return true;
+        }
+    }
+
+    false
+}
+
+/// Check if a node represents an unpacking assignment.
+pub fn is_unpacking_assignment(stmt: &Stmt) -> bool {
+    if let StmtKind::Assign { targets, value, .. } = &stmt.node {
+        if !targets.iter().any(|child| {
+            matches!(
+                child.node,
+                ExprKind::Set { .. } | ExprKind::List { .. } | ExprKind::Tuple { .. }
+            )
+        }) {
+            return false;
+        }
+        match &value.node {
+            ExprKind::Set { .. } | ExprKind::List { .. } | ExprKind::Tuple { .. } => return false,
+            _ => {}
+        }
+        return true;
+    }
+    false
+}
+
+/// Struct used to efficiently slice source code at (row, column) Locations.
+pub struct SourceCodeLocator<'a> {
+    content: &'a str,
+    offsets: Vec<usize>,
+    initialized: bool,
+}
+
+impl<'a> SourceCodeLocator<'a> {
+    pub fn new(content: &'a str) -> Self {
+        SourceCodeLocator {
+            content,
+            offsets: vec![],
+            initialized: false,
+        }
+    }
+
+    pub fn slice_source_code(&mut self, location: &Location) -> &'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 offset = self.offsets[location.row() - 1] + location.column() - 1;
+        &self.content[offset..]
+    }
+}

src/ast/relocate.rs

@@ -0,0 +1,137 @@
+use rustpython_parser::ast::{Expr, ExprKind, Keyword, Location};
+
+fn relocate_keyword(keyword: &mut Keyword, location: Location) {
+    keyword.location = 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: Location) {
+    expr.location = location;
+    match &mut expr.node {
+        ExprKind::BoolOp { values, .. } => {
+            for expr in values {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::NamedExpr { target, value } => {
+            relocate_expr(target, location);
+            relocate_expr(value, location);
+        }
+        ExprKind::BinOp { left, right, .. } => {
+            relocate_expr(left, location);
+            relocate_expr(right, location);
+        }
+        ExprKind::UnaryOp { operand, .. } => {
+            relocate_expr(operand, location);
+        }
+        ExprKind::Lambda { body, .. } => {
+            relocate_expr(body, location);
+        }
+        ExprKind::IfExp { test, body, orelse } => {
+            relocate_expr(test, location);
+            relocate_expr(body, location);
+            relocate_expr(orelse, location);
+        }
+        ExprKind::Dict { keys, values } => {
+            for expr in keys {
+                relocate_expr(expr, location);
+            }
+            for expr in values {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Set { elts } => {
+            for expr in elts {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::ListComp { elt, .. } => {
+            relocate_expr(elt, location);
+        }
+        ExprKind::SetComp { elt, .. } => {
+            relocate_expr(elt, location);
+        }
+        ExprKind::DictComp { key, value, .. } => {
+            relocate_expr(key, location);
+            relocate_expr(value, location);
+        }
+        ExprKind::GeneratorExp { elt, .. } => {
+            relocate_expr(elt, location);
+        }
+        ExprKind::Await { value } => relocate_expr(value, location),
+        ExprKind::Yield { value } => {
+            if let Some(expr) = value {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::YieldFrom { value } => relocate_expr(value, location),
+        ExprKind::Compare {
+            left, comparators, ..
+        } => {
+            relocate_expr(left, location);
+            for expr in comparators {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Call {
+            func,
+            args,
+            keywords,
+        } => {
+            relocate_expr(func, location);
+            for expr in args {
+                relocate_expr(expr, location);
+            }
+            for keyword in keywords {
+                relocate_keyword(keyword, location);
+            }
+        }
+        ExprKind::FormattedValue {
+            value, format_spec, ..
+        } => {
+            relocate_expr(value, location);
+            if let Some(expr) = format_spec {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::JoinedStr { values } => {
+            for expr in values {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Constant { .. } => {}
+        ExprKind::Attribute { value, .. } => {
+            relocate_expr(value, location);
+        }
+        ExprKind::Subscript { value, slice, .. } => {
+            relocate_expr(value, location);
+            relocate_expr(slice, location);
+        }
+        ExprKind::Starred { value, .. } => {
+            relocate_expr(value, location);
+        }
+        ExprKind::Name { .. } => {}
+        ExprKind::List { elts, .. } => {
+            for expr in elts {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Tuple { elts, .. } => {
+            for expr in elts {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Slice { lower, upper, step } => {
+            if let Some(expr) = lower {
+                relocate_expr(expr, location);
+            }
+            if let Some(expr) = upper {
+                relocate_expr(expr, location);
+            }
+            if let Some(expr) = step {
+                relocate_expr(expr, location);
+            }
+        }
+    }
+}

src/ast/types.rs

@@ -0,0 +1,71 @@
+use std::collections::BTreeMap;
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+use rustpython_parser::ast::Location;
+
+fn id() -> usize {
+    static COUNTER: AtomicUsize = AtomicUsize::new(1);
+    COUNTER.fetch_add(1, Ordering::Relaxed)
+}
+
+#[derive(Clone, Debug, Default)]
+pub struct FunctionScope {
+    pub uses_locals: bool,
+}
+
+#[derive(Clone, Debug)]
+pub enum ScopeKind {
+    Class,
+    Function(FunctionScope),
+    Generator,
+    Module,
+}
+
+#[derive(Clone, Debug)]
+pub struct Scope {
+    pub id: usize,
+    pub kind: ScopeKind,
+    pub import_starred: bool,
+    pub values: BTreeMap<String, Binding>,
+}
+
+impl Scope {
+    pub fn new(kind: ScopeKind) -> Self {
+        Scope {
+            id: id(),
+            kind,
+            import_starred: false,
+            values: BTreeMap::new(),
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub enum BindingKind {
+    Annotation,
+    Argument,
+    Assignment,
+    Binding,
+    LoopVar,
+    Builtin,
+    ClassDefinition,
+    Definition,
+    Export(Vec<String>),
+    FutureImportation,
+    Importation(String),
+    StarImportation,
+    SubmoduleImportation(String),
+}
+
+#[derive(Clone, Debug)]
+pub struct Binding {
+    pub kind: BindingKind,
+    pub location: Location,
+    /// Tuple of (scope index, location) indicating the scope and location at which the binding was
+    /// last used.
+    pub used: Option<(usize, Location)>,
+}
+
+pub trait CheckLocator {
+    fn locate_check(&self, default: Location) -> Location;
+}

src/ast/visitor.rs

@@ -4,64 +4,64 @@ use rustpython_parser::ast::{
     PatternKind, Stmt, StmtKind, Unaryop, Withitem,
 };
 
-pub trait Visitor {
-    fn visit_stmt(&mut self, stmt: &Stmt) {
+pub trait Visitor<'a> {
+    fn visit_stmt(&mut self, stmt: &'a Stmt) {
         walk_stmt(self, stmt);
     }
-    fn visit_annotation(&mut self, expr: &Expr) {
+    fn visit_annotation(&mut self, expr: &'a Expr) {
         walk_expr(self, expr);
     }
-    fn visit_expr(&mut self, expr: &Expr) {
+    fn visit_expr(&mut self, expr: &'a Expr) {
         walk_expr(self, expr);
     }
-    fn visit_constant(&mut self, constant: &Constant) {
+    fn visit_constant(&mut self, constant: &'a Constant) {
         walk_constant(self, constant);
     }
-    fn visit_expr_context(&mut self, expr_content: &ExprContext) {
+    fn visit_expr_context(&mut self, expr_content: &'a ExprContext) {
         walk_expr_context(self, expr_content);
     }
-    fn visit_boolop(&mut self, boolop: &Boolop) {
+    fn visit_boolop(&mut self, boolop: &'a Boolop) {
         walk_boolop(self, boolop);
     }
-    fn visit_operator(&mut self, operator: &Operator) {
+    fn visit_operator(&mut self, operator: &'a Operator) {
         walk_operator(self, operator);
     }
-    fn visit_unaryop(&mut self, unaryop: &Unaryop) {
+    fn visit_unaryop(&mut self, unaryop: &'a Unaryop) {
         walk_unaryop(self, unaryop);
     }
-    fn visit_cmpop(&mut self, cmpop: &Cmpop) {
+    fn visit_cmpop(&mut self, cmpop: &'a Cmpop) {
         walk_cmpop(self, cmpop);
     }
-    fn visit_comprehension(&mut self, comprehension: &Comprehension) {
+    fn visit_comprehension(&mut self, comprehension: &'a Comprehension) {
         walk_comprehension(self, comprehension);
     }
-    fn visit_excepthandler(&mut self, excepthandler: &Excepthandler) {
+    fn visit_excepthandler(&mut self, excepthandler: &'a Excepthandler) {
         walk_excepthandler(self, excepthandler);
     }
-    fn visit_arguments(&mut self, arguments: &Arguments) {
+    fn visit_arguments(&mut self, arguments: &'a Arguments) {
         walk_arguments(self, arguments);
     }
-    fn visit_arg(&mut self, arg: &Arg) {
+    fn visit_arg(&mut self, arg: &'a Arg) {
         walk_arg(self, arg);
     }
-    fn visit_keyword(&mut self, keyword: &Keyword) {
+    fn visit_keyword(&mut self, keyword: &'a Keyword) {
         walk_keyword(self, keyword);
     }
-    fn visit_alias(&mut self, alias: &Alias) {
+    fn visit_alias(&mut self, alias: &'a Alias) {
         walk_alias(self, alias);
     }
-    fn visit_withitem(&mut self, withitem: &Withitem) {
+    fn visit_withitem(&mut self, withitem: &'a Withitem) {
         walk_withitem(self, withitem);
     }
-    fn visit_match_case(&mut self, match_case: &MatchCase) {
+    fn visit_match_case(&mut self, match_case: &'a MatchCase) {
         walk_match_case(self, match_case);
     }
-    fn visit_pattern(&mut self, pattern: &Pattern) {
+    fn visit_pattern(&mut self, pattern: &'a Pattern) {
         walk_pattern(self, pattern);
     }
 }
 
-pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
+pub fn walk_stmt<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, stmt: &'a Stmt) {
     match &stmt.node {
         StmtKind::FunctionDef {
             args,
@@ -72,13 +72,13 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
         } => {
             visitor.visit_arguments(args);
             for expr in decorator_list {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
             for expr in returns {
                 visitor.visit_annotation(expr);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::AsyncFunctionDef {
@@ -90,13 +90,13 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
         } => {
             visitor.visit_arguments(args);
             for expr in decorator_list {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
             for expr in returns {
                 visitor.visit_annotation(expr);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::ClassDef {
@@ -107,33 +107,33 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             ..
         } => {
             for expr in bases {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
             for keyword in keywords {
-                visitor.visit_keyword(keyword)
-            }
-            for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_keyword(keyword);
             }
             for expr in decorator_list {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
+            }
+            for stmt in body {
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::Return { value } => {
             if let Some(expr) = value {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         StmtKind::Delete { targets } => {
             for expr in targets {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         StmtKind::Assign { targets, value, .. } => {
+            visitor.visit_expr(value);
             for expr in targets {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
-            visitor.visit_expr(value)
         }
         StmtKind::AugAssign { target, op, value } => {
             visitor.visit_expr(target);
@@ -146,11 +146,11 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             value,
             ..
         } => {
-            visitor.visit_expr(target);
             visitor.visit_annotation(annotation);
             if let Some(expr) = value {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
+            visitor.visit_expr(target);
         }
         StmtKind::For {
             target,
@@ -162,10 +162,10 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             visitor.visit_expr(target);
             visitor.visit_expr(iter);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::AsyncFor {
@@ -178,28 +178,28 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             visitor.visit_expr(target);
             visitor.visit_expr(iter);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::While { test, body, orelse } => {
             visitor.visit_expr(test);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::If { test, body, orelse } => {
             visitor.visit_expr(test);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::With { items, body, .. } => {
@@ -207,7 +207,7 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
                 visitor.visit_withitem(withitem);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::AsyncWith { items, body, .. } => {
@@ -215,7 +215,7 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
                 visitor.visit_withitem(withitem);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::Match { subject, cases } => {
@@ -227,10 +227,10 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
         }
         StmtKind::Raise { exc, cause } => {
             if let Some(expr) = exc {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             };
             if let Some(expr) = cause {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             };
         }
         StmtKind::Try {
@@ -240,22 +240,22 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             finalbody,
         } => {
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for excepthandler in handlers {
                 visitor.visit_excepthandler(excepthandler)
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in finalbody {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::Assert { test, msg } => {
             visitor.visit_expr(test);
             if let Some(expr) = msg {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         StmtKind::Import { names } => {
@@ -277,12 +277,12 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
     }
 }
 
-pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
+pub fn walk_expr<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, expr: &'a Expr) {
     match &expr.node {
         ExprKind::BoolOp { op, values } => {
             visitor.visit_boolop(op);
             for expr in values {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::NamedExpr { target, value } => {
@@ -309,26 +309,26 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
         }
         ExprKind::Dict { keys, values } => {
             for expr in keys {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
             for expr in values {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::Set { elts } => {
             for expr in elts {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::ListComp { elt, generators } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
             visitor.visit_expr(elt);
         }
         ExprKind::SetComp { elt, generators } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
             visitor.visit_expr(elt);
         }
@@ -338,21 +338,21 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
             generators,
         } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
             visitor.visit_expr(key);
             visitor.visit_expr(value);
         }
         ExprKind::GeneratorExp { elt, generators } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
             visitor.visit_expr(elt);
         }
         ExprKind::Await { value } => visitor.visit_expr(value),
         ExprKind::Yield { value } => {
             if let Some(expr) = value {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::YieldFrom { value } => visitor.visit_expr(value),
@@ -366,7 +366,7 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
                 visitor.visit_cmpop(cmpop);
             }
             for expr in comparators {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::Call {
@@ -387,12 +387,12 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
         } => {
             visitor.visit_expr(value);
             if let Some(expr) = format_spec {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::JoinedStr { values } => {
             for expr in values {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::Constant { value, .. } => visitor.visit_constant(value),
@@ -438,7 +438,7 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
     }
 }
 
-pub fn walk_constant<V: Visitor + ?Sized>(visitor: &mut V, constant: &Constant) {
+pub fn walk_constant<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, constant: &'a Constant) {
     if let Constant::Tuple(constants) = constant {
         for constant in constants {
             visitor.visit_constant(constant)
@@ -446,7 +446,10 @@ pub fn walk_constant<V: Visitor + ?Sized>(visitor: &mut V, constant: &Constant)
     }
 }
 
-pub fn walk_comprehension<V: Visitor + ?Sized>(visitor: &mut V, comprehension: &Comprehension) {
+pub fn walk_comprehension<'a, V: Visitor<'a> + ?Sized>(
+    visitor: &mut V,
+    comprehension: &'a Comprehension,
+) {
     visitor.visit_expr(&comprehension.target);
     visitor.visit_expr(&comprehension.iter);
     for expr in &comprehension.ifs {
@@ -454,7 +457,10 @@ pub fn walk_comprehension<V: Visitor + ?Sized>(visitor: &mut V, comprehension: &
     }
 }
 
-pub fn walk_excepthandler<V: Visitor + ?Sized>(visitor: &mut V, excepthandler: &Excepthandler) {
+pub fn walk_excepthandler<'a, V: Visitor<'a> + ?Sized>(
+    visitor: &mut V,
+    excepthandler: &'a Excepthandler,
+) {
     match &excepthandler.node {
         ExcepthandlerKind::ExceptHandler { type_, body, .. } => {
             if let Some(expr) = type_ {
@@ -467,7 +473,7 @@ pub fn walk_excepthandler<V: Visitor + ?Sized>(visitor: &mut V, excepthandler: &
     }
 }
 
-pub fn walk_arguments<V: Visitor + ?Sized>(visitor: &mut V, arguments: &Arguments) {
+pub fn walk_arguments<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, arguments: &'a Arguments) {
     for arg in &arguments.posonlyargs {
         visitor.visit_arg(arg);
     }
@@ -475,40 +481,40 @@ pub fn walk_arguments<V: Visitor + ?Sized>(visitor: &mut V, arguments: &Argument
         visitor.visit_arg(arg);
     }
     if let Some(arg) = &arguments.vararg {
-        visitor.visit_arg(arg)
+        visitor.visit_arg(arg);
     }
     for arg in &arguments.kwonlyargs {
         visitor.visit_arg(arg);
     }
     for expr in &arguments.kw_defaults {
-        visitor.visit_expr(expr)
+        visitor.visit_expr(expr);
     }
     if let Some(arg) = &arguments.kwarg {
-        visitor.visit_arg(arg)
+        visitor.visit_arg(arg);
     }
     for expr in &arguments.defaults {
-        visitor.visit_expr(expr)
+        visitor.visit_expr(expr);
     }
 }
 
-pub fn walk_arg<V: Visitor + ?Sized>(visitor: &mut V, arg: &Arg) {
+pub fn walk_arg<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, arg: &'a Arg) {
     if let Some(expr) = &arg.node.annotation {
-        visitor.visit_annotation(expr)
+        visitor.visit_annotation(expr);
     }
 }
 
-pub fn walk_keyword<V: Visitor + ?Sized>(visitor: &mut V, keyword: &Keyword) {
+pub fn walk_keyword<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, keyword: &'a Keyword) {
     visitor.visit_expr(&keyword.node.value);
 }
 
-pub fn walk_withitem<V: Visitor + ?Sized>(visitor: &mut V, withitem: &Withitem) {
+pub fn walk_withitem<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, withitem: &'a Withitem) {
     visitor.visit_expr(&withitem.context_expr);
     if let Some(expr) = &withitem.optional_vars {
         visitor.visit_expr(expr);
     }
 }
 
-pub fn walk_match_case<V: Visitor + ?Sized>(visitor: &mut V, match_case: &MatchCase) {
+pub fn walk_match_case<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, match_case: &'a MatchCase) {
     visitor.visit_pattern(&match_case.pattern);
     if let Some(expr) = &match_case.guard {
         visitor.visit_expr(expr);
@@ -518,13 +524,13 @@ pub fn walk_match_case<V: Visitor + ?Sized>(visitor: &mut V, match_case: &MatchC
     }
 }
 
-pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
+pub fn walk_pattern<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, pattern: &'a Pattern) {
     match &pattern.node {
         PatternKind::MatchValue { value } => visitor.visit_expr(value),
         PatternKind::MatchSingleton { value } => visitor.visit_constant(value),
         PatternKind::MatchSequence { patterns } => {
             for pattern in patterns {
-                visitor.visit_pattern(pattern)
+                visitor.visit_pattern(pattern);
             }
         }
         PatternKind::MatchMapping { keys, patterns, .. } => {
@@ -553,7 +559,7 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
         PatternKind::MatchStar { .. } => {}
         PatternKind::MatchAs { pattern, .. } => {
             if let Some(pattern) = pattern {
-                visitor.visit_pattern(pattern)
+                visitor.visit_pattern(pattern);
             }
         }
         PatternKind::MatchOr { patterns } => {
@@ -566,24 +572,28 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_expr_context<V: Visitor + ?Sized>(visitor: &mut V, expr_context: &ExprContext) {}
+pub fn walk_expr_context<'a, V: Visitor<'a> + ?Sized>(
+    visitor: &mut V,
+    expr_context: &'a ExprContext,
+) {
+}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_boolop<V: Visitor + ?Sized>(visitor: &mut V, boolop: &Boolop) {}
+pub fn walk_boolop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, boolop: &'a Boolop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_operator<V: Visitor + ?Sized>(visitor: &mut V, operator: &Operator) {}
+pub fn walk_operator<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, operator: &'a Operator) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_unaryop<V: Visitor + ?Sized>(visitor: &mut V, unaryop: &Unaryop) {}
+pub fn walk_unaryop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, unaryop: &'a Unaryop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_cmpop<V: Visitor + ?Sized>(visitor: &mut V, cmpop: &Cmpop) {}
+pub fn walk_cmpop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, cmpop: &'a Cmpop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_alias<V: Visitor + ?Sized>(visitor: &mut V, alias: &Alias) {}
+pub fn walk_alias<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, alias: &'a Alias) {}

src/autofix.rs

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

src/autofix/fixer.rs

@@ -0,0 +1,15 @@
+#[derive(Hash)]
+pub enum Mode {
+    Generate,
+    Apply,
+    None,
+}
+
+impl From<bool> for Mode {
+    fn from(value: bool) -> Self {
+        match value {
+            true => Mode::Apply,
+            false => Mode::None,
+        }
+    }
+}

src/autofix/fixes.rs

@@ -0,0 +1,126 @@
+use rustpython_parser::ast::{Expr, Keyword, Location};
+use rustpython_parser::lexer;
+use rustpython_parser::token::Tok;
+
+use crate::ast::operations::SourceCodeLocator;
+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(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(),
+                start,
+                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(),
+                start,
+                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(),
+                start,
+                end,
+                applied: false,
+            }),
+            _ => None,
+        }
+    }
+}

src/cache.rs

@@ -1,126 +0,0 @@
-use std::collections::hash_map::DefaultHasher;
-use std::hash::{Hash, Hasher};
-use std::path::Path;
-
-use cacache::Error::EntryNotFound;
-use filetime::FileTime;
-use log::error;
-use serde::{Deserialize, Serialize};
-
-use crate::message::Message;
-use crate::settings::Settings;
-
-const VERSION: &str = env!("CARGO_PKG_VERSION");
-
-#[derive(Serialize, Deserialize)]
-struct CacheMetadata {
-    mtime: i64,
-}
-
-#[derive(Serialize)]
-struct CheckResultRef<'a> {
-    metadata: &'a CacheMetadata,
-    messages: &'a [Message],
-}
-
-#[derive(Deserialize)]
-struct CheckResult {
-    metadata: CacheMetadata,
-    messages: Vec<Message>,
-}
-
-pub enum Mode {
-    ReadWrite,
-    ReadOnly,
-    WriteOnly,
-    None,
-}
-
-impl Mode {
-    fn allow_read(&self) -> bool {
-        match self {
-            Mode::ReadWrite => true,
-            Mode::ReadOnly => true,
-            Mode::WriteOnly => false,
-            Mode::None => false,
-        }
-    }
-
-    fn allow_write(&self) -> bool {
-        match self {
-            Mode::ReadWrite => true,
-            Mode::ReadOnly => false,
-            Mode::WriteOnly => true,
-            Mode::None => false,
-        }
-    }
-}
-
-impl From<bool> for Mode {
-    fn from(value: bool) -> Self {
-        match value {
-            true => Mode::ReadWrite,
-            false => Mode::WriteOnly,
-        }
-    }
-}
-
-fn cache_dir() -> &'static str {
-    "./.cache"
-}
-
-fn cache_key(path: &Path, settings: &Settings) -> String {
-    let mut hasher = DefaultHasher::new();
-    settings.hash(&mut hasher);
-    format!(
-        "{}@{}@{}",
-        path.canonicalize().unwrap().to_string_lossy(),
-        VERSION,
-        hasher.finish()
-    )
-}
-
-pub fn get(path: &Path, settings: &Settings, mode: &Mode) -> Option<Vec<Message>> {
-    if !mode.allow_read() {
-        return None;
-    };
-
-    match cacache::read_sync(cache_dir(), cache_key(path, settings)) {
-        Ok(encoded) => match path.metadata() {
-            Ok(m) => match bincode::deserialize::<CheckResult>(&encoded[..]) {
-                Ok(CheckResult { metadata, messages }) => {
-                    if FileTime::from_last_modification_time(&m).unix_seconds() == metadata.mtime {
-                        return Some(messages);
-                    }
-                }
-                Err(e) => error!("Failed to deserialize encoded cache entry: {e:?}"),
-            },
-            Err(e) => error!("Failed to read metadata from path: {e:?}"),
-        },
-        Err(EntryNotFound(_, _)) => {}
-        Err(e) => error!("Failed to read from cache: {e:?}"),
-    }
-    None
-}
-
-pub fn set(path: &Path, settings: &Settings, messages: &[Message], mode: &Mode) {
-    if !mode.allow_write() {
-        return;
-    };
-
-    if let Ok(metadata) = path.metadata() {
-        let check_result = CheckResultRef {
-            metadata: &CacheMetadata {
-                mtime: FileTime::from_last_modification_time(&metadata).unix_seconds(),
-            },
-            messages,
-        };
-        if let Err(e) = cacache::write_sync(
-            cache_dir(),
-            cache_key(path, settings),
-            bincode::serialize(&check_result).unwrap(),
-        ) {
-            error!("Failed to write to cache: {e:?}")
-        }
-    }
-}

src/check_lines.rs

@@ -1,10 +1,26 @@
 use rustpython_parser::ast::Location;
 
-use crate::checks::{Check, CheckKind};
+use crate::checks::{Check, CheckCode, CheckKind};
 use crate::settings::Settings;
 
+/// Whether the given line is too long and should be reported.
+fn should_enforce_line_length(line: &str, length: usize, limit: usize) -> bool {
+    if length > limit {
+        let mut chunks = line.split_whitespace();
+        if let (Some(first), Some(_)) = (chunks.next(), chunks.next()) {
+            // Do not enforce the line length for commented lines with a single word
+            !(first == "#" && chunks.next().is_none())
+        } else {
+            // Single word / no printable chars - no way to make the line shorter
+            false
+        }
+    } else {
+        false
+    }
+}
+
 pub fn check_lines(checks: &mut Vec<Check>, contents: &str, settings: &Settings) {
-    let enforce_line_too_ling = settings.select.contains(CheckKind::LineTooLong.code());
+    let enforce_line_too_long = settings.select.contains(&CheckCode::E501);
 
     let mut line_checks = vec![];
     let mut ignored = vec![];
@@ -18,13 +34,13 @@ pub fn check_lines(checks: &mut Vec<Check>, contents: &str, settings: &Settings)
         }
 
         // Enforce line length.
-        if enforce_line_too_ling && line.len() > settings.line_length {
-            let chunks: Vec<&str> = line.split_whitespace().collect();
-            if !(chunks.len() == 1 || (chunks.len() == 2 && chunks[0] == "#")) {
-                let check = Check {
-                    kind: CheckKind::LineTooLong,
-                    location: Location::new(row + 1, settings.line_length + 1),
-                };
+        if enforce_line_too_long {
+            let line_length = line.chars().count();
+            if should_enforce_line_length(line, line_length, settings.line_length) {
+                let check = Check::new(
+                    CheckKind::LineTooLong(line_length, settings.line_length),
+                    Location::new(row + 1, settings.line_length + 1),
+                );
                 if !check.is_inline_ignored(line) {
                     line_checks.push(check);
                 }
@@ -37,3 +53,31 @@ pub fn check_lines(checks: &mut Vec<Check>, contents: &str, settings: &Settings)
     }
     checks.extend(line_checks);
 }
+
+#[cfg(test)]
+mod tests {
+    use std::collections::BTreeSet;
+
+    use super::check_lines;
+    use super::*;
+
+    #[test]
+    fn e501_non_ascii_char() {
+        let line = "'\u{4e9c}' * 2"; // 7 in UTF-32, 9 in UTF-8.
+        let check_with_max_line_length = |line_length: usize| {
+            let mut checks: Vec<Check> = vec![];
+            let settings = Settings {
+                pyproject: None,
+                project_root: None,
+                line_length,
+                exclude: vec![],
+                extend_exclude: vec![],
+                select: BTreeSet::from_iter(vec![CheckCode::E501]),
+            };
+            check_lines(&mut checks, line, &settings);
+            return checks;
+        };
+        assert!(!check_with_max_line_length(6).is_empty());
+        assert!(check_with_max_line_length(7).is_empty());
+    }
+}

src/checks.rs

@@ -1,24 +1,104 @@
 use std::str::FromStr;
 
 use anyhow::Result;
+use once_cell::sync::Lazy;
 use regex::Regex;
 use rustpython_parser::ast::Location;
 use serde::{Deserialize, Serialize};
 
-#[derive(Debug, PartialEq, Eq, Serialize, Deserialize, Hash, PartialOrd, Ord)]
+pub const ALL_CHECK_CODES: [CheckCode; 44] = [
+    CheckCode::E402,
+    CheckCode::E501,
+    CheckCode::E711,
+    CheckCode::E712,
+    CheckCode::E713,
+    CheckCode::E714,
+    CheckCode::E721,
+    CheckCode::E722,
+    CheckCode::E731,
+    CheckCode::E741,
+    CheckCode::E742,
+    CheckCode::E743,
+    CheckCode::E902,
+    CheckCode::E999,
+    CheckCode::F401,
+    CheckCode::F402,
+    CheckCode::F403,
+    CheckCode::F404,
+    CheckCode::F405,
+    CheckCode::F406,
+    CheckCode::F407,
+    CheckCode::F541,
+    CheckCode::F601,
+    CheckCode::F602,
+    CheckCode::F621,
+    CheckCode::F622,
+    CheckCode::F631,
+    CheckCode::F632,
+    CheckCode::F633,
+    CheckCode::F634,
+    CheckCode::F701,
+    CheckCode::F702,
+    CheckCode::F704,
+    CheckCode::F706,
+    CheckCode::F707,
+    CheckCode::F722,
+    CheckCode::F821,
+    CheckCode::F822,
+    CheckCode::F823,
+    CheckCode::F831,
+    CheckCode::F841,
+    CheckCode::F901,
+    CheckCode::R001,
+    CheckCode::R002,
+];
+
+#[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize, Hash, PartialOrd, Ord)]
 pub enum CheckCode {
+    E402,
     E501,
+    E711,
+    E712,
+    E713,
+    E714,
+    E721,
+    E722,
+    E731,
+    E741,
+    E742,
+    E743,
+    E902,
+    E999,
     F401,
+    F402,
     F403,
+    F404,
+    F405,
+    F406,
+    F407,
     F541,
+    F601,
+    F602,
+    F621,
+    F622,
+    F631,
+    F632,
+    F633,
     F634,
+    F701,
+    F702,
     F704,
     F706,
+    F707,
+    F722,
     F821,
+    F822,
+    F823,
     F831,
-    F832,
     F841,
     F901,
+    R001,
+    R002,
 }
 
 impl FromStr for CheckCode {
@@ -26,18 +106,50 @@ impl FromStr for CheckCode {
 
     fn from_str(s: &str) -> Result<Self> {
         match s {
+            "E402" => Ok(CheckCode::E402),
             "E501" => Ok(CheckCode::E501),
+            "E711" => Ok(CheckCode::E711),
+            "E712" => Ok(CheckCode::E712),
+            "E713" => Ok(CheckCode::E713),
+            "E714" => Ok(CheckCode::E714),
+            "E721" => Ok(CheckCode::E721),
+            "E722" => Ok(CheckCode::E722),
+            "E731" => Ok(CheckCode::E731),
+            "E741" => Ok(CheckCode::E741),
+            "E742" => Ok(CheckCode::E742),
+            "E743" => Ok(CheckCode::E743),
+            "E902" => Ok(CheckCode::E902),
+            "E999" => Ok(CheckCode::E999),
             "F401" => Ok(CheckCode::F401),
+            "F402" => Ok(CheckCode::F402),
             "F403" => Ok(CheckCode::F403),
+            "F404" => Ok(CheckCode::F404),
+            "F405" => Ok(CheckCode::F405),
+            "F406" => Ok(CheckCode::F406),
+            "F407" => Ok(CheckCode::F407),
             "F541" => Ok(CheckCode::F541),
+            "F601" => Ok(CheckCode::F601),
+            "F602" => Ok(CheckCode::F602),
+            "F621" => Ok(CheckCode::F621),
+            "F622" => Ok(CheckCode::F622),
+            "F631" => Ok(CheckCode::F631),
+            "F632" => Ok(CheckCode::F632),
+            "F633" => Ok(CheckCode::F633),
             "F634" => Ok(CheckCode::F634),
+            "F701" => Ok(CheckCode::F701),
+            "F702" => Ok(CheckCode::F702),
             "F704" => Ok(CheckCode::F704),
             "F706" => Ok(CheckCode::F706),
+            "F707" => Ok(CheckCode::F707),
+            "F722" => Ok(CheckCode::F722),
             "F821" => Ok(CheckCode::F821),
+            "F822" => Ok(CheckCode::F822),
+            "F823" => Ok(CheckCode::F823),
             "F831" => Ok(CheckCode::F831),
-            "F832" => Ok(CheckCode::F832),
             "F841" => Ok(CheckCode::F841),
             "F901" => Ok(CheckCode::F901),
+            "R001" => Ok(CheckCode::R001),
+            "R002" => Ok(CheckCode::R002),
             _ => Err(anyhow::anyhow!("Unknown check code: {s}")),
         }
     }
@@ -46,36 +158,109 @@ impl FromStr for CheckCode {
 impl CheckCode {
     pub fn as_str(&self) -> &str {
         match self {
+            CheckCode::E402 => "E402",
             CheckCode::E501 => "E501",
+            CheckCode::E711 => "E711",
+            CheckCode::E712 => "E712",
+            CheckCode::E713 => "E713",
+            CheckCode::E714 => "E714",
+            CheckCode::E721 => "E721",
+            CheckCode::E722 => "E722",
+            CheckCode::E731 => "E731",
+            CheckCode::E741 => "E741",
+            CheckCode::E742 => "E742",
+            CheckCode::E743 => "E743",
+            CheckCode::E902 => "E902",
+            CheckCode::E999 => "E999",
             CheckCode::F401 => "F401",
+            CheckCode::F402 => "F402",
             CheckCode::F403 => "F403",
+            CheckCode::F404 => "F404",
+            CheckCode::F405 => "F405",
+            CheckCode::F406 => "F406",
+            CheckCode::F407 => "F407",
             CheckCode::F541 => "F541",
+            CheckCode::F601 => "F601",
+            CheckCode::F602 => "F602",
+            CheckCode::F621 => "F621",
+            CheckCode::F622 => "F622",
+            CheckCode::F631 => "F631",
+            CheckCode::F632 => "F632",
+            CheckCode::F633 => "F633",
             CheckCode::F634 => "F634",
+            CheckCode::F701 => "F701",
+            CheckCode::F702 => "F702",
             CheckCode::F704 => "F704",
             CheckCode::F706 => "F706",
+            CheckCode::F707 => "F707",
+            CheckCode::F722 => "F722",
             CheckCode::F821 => "F821",
+            CheckCode::F822 => "F822",
+            CheckCode::F823 => "F823",
             CheckCode::F831 => "F831",
-            CheckCode::F832 => "F832",
             CheckCode::F841 => "F841",
             CheckCode::F901 => "F901",
+            CheckCode::R001 => "R001",
+            CheckCode::R002 => "R002",
         }
     }
 
-    /// The source for the check (either the AST, or the physical lines).
+    /// The source for the check (either the AST, the filesystem, or the physical lines).
     pub fn lint_source(&self) -> &'static LintSource {
         match self {
             CheckCode::E501 => &LintSource::Lines,
-            CheckCode::F401 => &LintSource::AST,
-            CheckCode::F403 => &LintSource::AST,
-            CheckCode::F541 => &LintSource::AST,
-            CheckCode::F634 => &LintSource::AST,
-            CheckCode::F704 => &LintSource::AST,
-            CheckCode::F706 => &LintSource::AST,
-            CheckCode::F821 => &LintSource::AST,
-            CheckCode::F831 => &LintSource::AST,
-            CheckCode::F832 => &LintSource::AST,
-            CheckCode::F841 => &LintSource::AST,
-            CheckCode::F901 => &LintSource::AST,
+            CheckCode::E902 | CheckCode::E999 => &LintSource::FileSystem,
+            _ => &LintSource::AST,
+        }
+    }
+
+    /// A placeholder representation of the CheckKind for the check.
+    pub fn kind(&self) -> CheckKind {
+        match self {
+            CheckCode::E402 => CheckKind::ModuleImportNotAtTopOfFile,
+            CheckCode::E501 => CheckKind::LineTooLong(89, 88),
+            CheckCode::E711 => CheckKind::NoneComparison(RejectedCmpop::Eq),
+            CheckCode::E712 => CheckKind::TrueFalseComparison(true, RejectedCmpop::Eq),
+            CheckCode::E713 => CheckKind::NotInTest,
+            CheckCode::E714 => CheckKind::NotIsTest,
+            CheckCode::E721 => CheckKind::TypeComparison,
+            CheckCode::E722 => CheckKind::DoNotUseBareExcept,
+            CheckCode::E731 => CheckKind::DoNotAssignLambda,
+            CheckCode::E741 => CheckKind::AmbiguousVariableName("...".to_string()),
+            CheckCode::E742 => CheckKind::AmbiguousClassName("...".to_string()),
+            CheckCode::E743 => CheckKind::AmbiguousFunctionName("...".to_string()),
+            CheckCode::E902 => CheckKind::IOError("...".to_string()),
+            CheckCode::E999 => CheckKind::SyntaxError("...".to_string()),
+            CheckCode::F401 => CheckKind::UnusedImport("...".to_string()),
+            CheckCode::F402 => CheckKind::ImportShadowedByLoopVar("...".to_string(), 1),
+            CheckCode::F403 => CheckKind::ImportStarUsed("...".to_string()),
+            CheckCode::F404 => CheckKind::LateFutureImport,
+            CheckCode::F405 => CheckKind::ImportStarUsage("...".to_string(), "...".to_string()),
+            CheckCode::F406 => CheckKind::ImportStarNotPermitted("...".to_string()),
+            CheckCode::F407 => CheckKind::FutureFeatureNotDefined("...".to_string()),
+            CheckCode::F541 => CheckKind::FStringMissingPlaceholders,
+            CheckCode::F601 => CheckKind::MultiValueRepeatedKeyLiteral,
+            CheckCode::F602 => CheckKind::MultiValueRepeatedKeyVariable("...".to_string()),
+            CheckCode::F621 => CheckKind::TooManyExpressionsInStarredAssignment,
+            CheckCode::F622 => CheckKind::TwoStarredExpressions,
+            CheckCode::F631 => CheckKind::AssertTuple,
+            CheckCode::F632 => CheckKind::IsLiteral,
+            CheckCode::F633 => CheckKind::InvalidPrintSyntax,
+            CheckCode::F634 => CheckKind::IfTuple,
+            CheckCode::F701 => CheckKind::BreakOutsideLoop,
+            CheckCode::F702 => CheckKind::ContinueOutsideLoop,
+            CheckCode::F704 => CheckKind::YieldOutsideFunction,
+            CheckCode::F706 => CheckKind::ReturnOutsideFunction,
+            CheckCode::F707 => CheckKind::DefaultExceptNotLast,
+            CheckCode::F722 => CheckKind::ForwardAnnotationSyntaxError("...".to_string()),
+            CheckCode::F821 => CheckKind::UndefinedName("...".to_string()),
+            CheckCode::F822 => CheckKind::UndefinedExport("...".to_string()),
+            CheckCode::F823 => CheckKind::UndefinedLocal("...".to_string()),
+            CheckCode::F831 => CheckKind::DuplicateArgumentName,
+            CheckCode::F841 => CheckKind::UnusedVariable("...".to_string()),
+            CheckCode::F901 => CheckKind::RaiseNotImplemented,
+            CheckCode::R001 => CheckKind::UselessObjectInheritance("...".to_string()),
+            CheckCode::R002 => CheckKind::NoAssertEquals,
         }
     }
 }
@@ -84,94 +269,343 @@ impl CheckCode {
 pub enum LintSource {
     AST,
     Lines,
+    FileSystem,
+}
+
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub enum RejectedCmpop {
+    Eq,
+    NotEq,
 }
 
 #[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub enum CheckKind {
+    AmbiguousClassName(String),
+    AmbiguousFunctionName(String),
+    AmbiguousVariableName(String),
+    AssertTuple,
+    BreakOutsideLoop,
+    ContinueOutsideLoop,
+    DefaultExceptNotLast,
+    DoNotAssignLambda,
+    DoNotUseBareExcept,
     DuplicateArgumentName,
+    ForwardAnnotationSyntaxError(String),
     FStringMissingPlaceholders,
+    FutureFeatureNotDefined(String),
+    IOError(String),
     IfTuple,
-    ImportStarUsage,
-    LineTooLong,
+    ImportShadowedByLoopVar(String, usize),
+    ImportStarNotPermitted(String),
+    ImportStarUsage(String, String),
+    ImportStarUsed(String),
+    InvalidPrintSyntax,
+    IsLiteral,
+    LateFutureImport,
+    LineTooLong(usize, usize),
+    ModuleImportNotAtTopOfFile,
+    MultiValueRepeatedKeyLiteral,
+    MultiValueRepeatedKeyVariable(String),
+    NoAssertEquals,
+    NoneComparison(RejectedCmpop),
+    NotInTest,
+    NotIsTest,
     RaiseNotImplemented,
-    YieldOutsideFunction,
     ReturnOutsideFunction,
-    UndefinedName(String),
+    SyntaxError(String),
+    TooManyExpressionsInStarredAssignment,
+    TrueFalseComparison(bool, RejectedCmpop),
+    TwoStarredExpressions,
+    TypeComparison,
+    UndefinedExport(String),
     UndefinedLocal(String),
-    UnusedVariable(String),
+    UndefinedName(String),
     UnusedImport(String),
+    UnusedVariable(String),
+    UselessObjectInheritance(String),
+    YieldOutsideFunction,
 }
 
 impl CheckKind {
+    /// The name of the check.
+    pub fn name(&self) -> &'static str {
+        match self {
+            CheckKind::AmbiguousClassName(_) => "AmbiguousClassName",
+            CheckKind::AmbiguousFunctionName(_) => "AmbiguousFunctionName",
+            CheckKind::AmbiguousVariableName(_) => "AmbiguousVariableName",
+            CheckKind::AssertTuple => "AssertTuple",
+            CheckKind::BreakOutsideLoop => "BreakOutsideLoop",
+            CheckKind::ContinueOutsideLoop => "ContinueOutsideLoop",
+            CheckKind::DefaultExceptNotLast => "DefaultExceptNotLast",
+            CheckKind::DoNotAssignLambda => "DoNotAssignLambda",
+            CheckKind::DoNotUseBareExcept => "DoNotUseBareExcept",
+            CheckKind::DuplicateArgumentName => "DuplicateArgumentName",
+            CheckKind::FStringMissingPlaceholders => "FStringMissingPlaceholders",
+            CheckKind::ForwardAnnotationSyntaxError(_) => "ForwardAnnotationSyntaxError",
+            CheckKind::FutureFeatureNotDefined(_) => "FutureFeatureNotDefined",
+            CheckKind::IOError(_) => "IOError",
+            CheckKind::IfTuple => "IfTuple",
+            CheckKind::ImportShadowedByLoopVar(_, _) => "ImportShadowedByLoopVar",
+            CheckKind::ImportStarNotPermitted(_) => "ImportStarNotPermitted",
+            CheckKind::ImportStarUsage(_, _) => "ImportStarUsage",
+            CheckKind::ImportStarUsed(_) => "ImportStarUsed",
+            CheckKind::InvalidPrintSyntax => "InvalidPrintSyntax",
+            CheckKind::IsLiteral => "IsLiteral",
+            CheckKind::LateFutureImport => "LateFutureImport",
+            CheckKind::LineTooLong(_, _) => "LineTooLong",
+            CheckKind::ModuleImportNotAtTopOfFile => "ModuleImportNotAtTopOfFile",
+            CheckKind::MultiValueRepeatedKeyLiteral => "MultiValueRepeatedKeyLiteral",
+            CheckKind::MultiValueRepeatedKeyVariable(_) => "MultiValueRepeatedKeyVariable",
+            CheckKind::NoAssertEquals => "NoAssertEquals",
+            CheckKind::NoneComparison(_) => "NoneComparison",
+            CheckKind::NotInTest => "NotInTest",
+            CheckKind::NotIsTest => "NotIsTest",
+            CheckKind::RaiseNotImplemented => "RaiseNotImplemented",
+            CheckKind::ReturnOutsideFunction => "ReturnOutsideFunction",
+            CheckKind::SyntaxError(_) => "SyntaxError",
+            CheckKind::TooManyExpressionsInStarredAssignment => {
+                "TooManyExpressionsInStarredAssignment"
+            }
+            CheckKind::TrueFalseComparison(_, _) => "TrueFalseComparison",
+            CheckKind::TwoStarredExpressions => "TwoStarredExpressions",
+            CheckKind::TypeComparison => "TypeComparison",
+            CheckKind::UndefinedExport(_) => "UndefinedExport",
+            CheckKind::UndefinedLocal(_) => "UndefinedLocal",
+            CheckKind::UndefinedName(_) => "UndefinedName",
+            CheckKind::UnusedImport(_) => "UnusedImport",
+            CheckKind::UnusedVariable(_) => "UnusedVariable",
+            CheckKind::UselessObjectInheritance(_) => "UselessObjectInheritance",
+            CheckKind::YieldOutsideFunction => "YieldOutsideFunction",
+        }
+    }
+
     /// A four-letter shorthand code for the check.
     pub fn code(&self) -> &'static CheckCode {
         match self {
+            CheckKind::AmbiguousClassName(_) => &CheckCode::E742,
+            CheckKind::AmbiguousFunctionName(_) => &CheckCode::E743,
+            CheckKind::AmbiguousVariableName(_) => &CheckCode::E741,
+            CheckKind::AssertTuple => &CheckCode::F631,
+            CheckKind::BreakOutsideLoop => &CheckCode::F701,
+            CheckKind::ContinueOutsideLoop => &CheckCode::F702,
+            CheckKind::DefaultExceptNotLast => &CheckCode::F707,
+            CheckKind::DoNotAssignLambda => &CheckCode::E731,
+            CheckKind::DoNotUseBareExcept => &CheckCode::E722,
             CheckKind::DuplicateArgumentName => &CheckCode::F831,
             CheckKind::FStringMissingPlaceholders => &CheckCode::F541,
+            CheckKind::ForwardAnnotationSyntaxError(_) => &CheckCode::F722,
+            CheckKind::FutureFeatureNotDefined(_) => &CheckCode::F407,
+            CheckKind::IOError(_) => &CheckCode::E902,
             CheckKind::IfTuple => &CheckCode::F634,
-            CheckKind::ImportStarUsage => &CheckCode::F403,
-            CheckKind::LineTooLong => &CheckCode::E501,
+            CheckKind::ImportShadowedByLoopVar(_, _) => &CheckCode::F402,
+            CheckKind::ImportStarNotPermitted(_) => &CheckCode::F406,
+            CheckKind::ImportStarUsed(_) => &CheckCode::F403,
+            CheckKind::ImportStarUsage(_, _) => &CheckCode::F405,
+            CheckKind::InvalidPrintSyntax => &CheckCode::F633,
+            CheckKind::IsLiteral => &CheckCode::F632,
+            CheckKind::LateFutureImport => &CheckCode::F404,
+            CheckKind::LineTooLong(_, _) => &CheckCode::E501,
+            CheckKind::ModuleImportNotAtTopOfFile => &CheckCode::E402,
+            CheckKind::MultiValueRepeatedKeyLiteral => &CheckCode::F601,
+            CheckKind::MultiValueRepeatedKeyVariable(_) => &CheckCode::F602,
+            CheckKind::NoAssertEquals => &CheckCode::R002,
+            CheckKind::NoneComparison(_) => &CheckCode::E711,
+            CheckKind::NotInTest => &CheckCode::E713,
+            CheckKind::NotIsTest => &CheckCode::E714,
             CheckKind::RaiseNotImplemented => &CheckCode::F901,
-            CheckKind::YieldOutsideFunction => &CheckCode::F704,
             CheckKind::ReturnOutsideFunction => &CheckCode::F706,
+            CheckKind::SyntaxError(_) => &CheckCode::E999,
+            CheckKind::TooManyExpressionsInStarredAssignment => &CheckCode::F621,
+            CheckKind::TrueFalseComparison(_, _) => &CheckCode::E712,
+            CheckKind::TwoStarredExpressions => &CheckCode::F622,
+            CheckKind::TypeComparison => &CheckCode::E721,
+            CheckKind::UndefinedExport(_) => &CheckCode::F822,
+            CheckKind::UndefinedLocal(_) => &CheckCode::F823,
             CheckKind::UndefinedName(_) => &CheckCode::F821,
-            CheckKind::UndefinedLocal(_) => &CheckCode::F832,
-            CheckKind::UnusedVariable(_) => &CheckCode::F841,
             CheckKind::UnusedImport(_) => &CheckCode::F401,
+            CheckKind::UnusedVariable(_) => &CheckCode::F841,
+            CheckKind::UselessObjectInheritance(_) => &CheckCode::R001,
+            CheckKind::YieldOutsideFunction => &CheckCode::F704,
         }
     }
 
     /// The body text for the check.
     pub fn body(&self) -> String {
         match self {
+            CheckKind::AmbiguousClassName(name) => {
+                format!("ambiguous class name '{}'", name)
+            }
+            CheckKind::AmbiguousFunctionName(name) => {
+                format!("ambiguous function name '{}'", name)
+            }
+            CheckKind::AmbiguousVariableName(name) => {
+                format!("ambiguous variable name '{}'", name)
+            }
+            CheckKind::AssertTuple => {
+                "Assert test is a non-empty tuple, which is always `True`".to_string()
+            }
+            CheckKind::BreakOutsideLoop => "`break` outside loop".to_string(),
+            CheckKind::ContinueOutsideLoop => "`continue` not properly in loop".to_string(),
+            CheckKind::DefaultExceptNotLast => {
+                "an `except:` block as not the last exception handler".to_string()
+            }
+            CheckKind::DoNotAssignLambda => {
+                "Do not assign a lambda expression, use a def".to_string()
+            }
+            CheckKind::DoNotUseBareExcept => "Do not use bare `except`".to_string(),
             CheckKind::DuplicateArgumentName => {
                 "Duplicate argument name in function definition".to_string()
             }
+            CheckKind::ForwardAnnotationSyntaxError(body) => {
+                format!("syntax error in forward annotation '{body}'")
+            }
             CheckKind::FStringMissingPlaceholders => {
                 "f-string without any placeholders".to_string()
             }
-            CheckKind::IfTuple => {
-                "If test is a tuple.to_string(), which is always `True`".to_string()
+            CheckKind::FutureFeatureNotDefined(name) => {
+                format!("future feature '{name}' is not defined")
             }
-            CheckKind::ImportStarUsage => "Unable to detect undefined names".to_string(),
-            CheckKind::LineTooLong => "Line too long".to_string(),
+            CheckKind::IOError(message) => message.clone(),
+            CheckKind::IfTuple => "If test is a tuple, which is always `True`".to_string(),
+            CheckKind::InvalidPrintSyntax => "use of >> is invalid with print function".to_string(),
+            CheckKind::ImportShadowedByLoopVar(name, line) => {
+                format!("import '{name}' from line {line} shadowed by loop variable")
+            }
+            CheckKind::ImportStarNotPermitted(name) => {
+                format!("`from {name} import *` only allowed at module level")
+            }
+            CheckKind::ImportStarUsed(name) => {
+                format!("`from {name} import *` used; unable to detect undefined names")
+            }
+            CheckKind::ImportStarUsage(name, sources) => {
+                format!("'{name}' may be undefined, or defined from star imports: {sources}")
+            }
+            CheckKind::IsLiteral => "use ==/!= to compare constant literals".to_string(),
+            CheckKind::LateFutureImport => {
+                "from __future__ imports must occur at the beginning of the file".to_string()
+            }
+            CheckKind::LineTooLong(length, limit) => {
+                format!("Line too long ({length} > {limit} characters)")
+            }
+            CheckKind::ModuleImportNotAtTopOfFile => {
+                "Module level import not at top of file".to_string()
+            }
+            CheckKind::MultiValueRepeatedKeyLiteral => {
+                "Dictionary key literal repeated".to_string()
+            }
+            CheckKind::MultiValueRepeatedKeyVariable(name) => {
+                format!("Dictionary key `{name}` repeated")
+            }
+            CheckKind::NoAssertEquals => {
+                "`assertEquals` is deprecated, use `assertEqual` instead".to_string()
+            }
+            CheckKind::NoneComparison(op) => match op {
+                RejectedCmpop::Eq => "Comparison to `None` should be `cond is None`".to_string(),
+                RejectedCmpop::NotEq => {
+                    "Comparison to `None` should be `cond is not None`".to_string()
+                }
+            },
+            CheckKind::NotInTest => "Test for membership should be `not in`".to_string(),
+            CheckKind::NotIsTest => "Test for object identity should be `is not`".to_string(),
             CheckKind::RaiseNotImplemented => {
-                "'raise NotImplemented' should be 'raise NotImplementedError".to_string()
-            }
-            CheckKind::YieldOutsideFunction => {
-                "a `yield` or `yield from` statement outside of a function/method".to_string()
+                "`raise NotImplemented` should be `raise NotImplementedError`".to_string()
             }
             CheckKind::ReturnOutsideFunction => {
                 "a `return` statement outside of a function/method".to_string()
             }
-            CheckKind::UndefinedName(name) => {
-                format!("Undefined name `{name}`")
+            CheckKind::SyntaxError(message) => format!("SyntaxError: {message}"),
+            CheckKind::TooManyExpressionsInStarredAssignment => {
+                "too many expressions in star-unpacking assignment".to_string()
             }
-            CheckKind::UnusedVariable(name) => {
-                format!("Local variable `{name}` is assigned to but never used")
+            CheckKind::TrueFalseComparison(value, op) => match *value {
+                true => match op {
+                    RejectedCmpop::Eq => {
+                        "Comparison to `True` should be `cond is True`".to_string()
+                    }
+                    RejectedCmpop::NotEq => {
+                        "Comparison to `True` should be `cond is not True`".to_string()
+                    }
+                },
+                false => match op {
+                    RejectedCmpop::Eq => {
+                        "Comparison to `False` should be `cond is False`".to_string()
+                    }
+                    RejectedCmpop::NotEq => {
+                        "Comparison to `False` should be `cond is not False`".to_string()
+                    }
+                },
+            },
+            CheckKind::TwoStarredExpressions => "two starred expressions in assignment".to_string(),
+            CheckKind::TypeComparison => "do not compare types, use `isinstance()`".to_string(),
+            CheckKind::UndefinedExport(name) => {
+                format!("Undefined name `{name}` in `__all__`")
             }
             CheckKind::UndefinedLocal(name) => {
                 format!("Local variable `{name}` referenced before assignment")
             }
+            CheckKind::UndefinedName(name) => {
+                format!("Undefined name `{name}`")
+            }
             CheckKind::UnusedImport(name) => format!("`{name}` imported but unused"),
+            CheckKind::UnusedVariable(name) => {
+                format!("Local variable `{name}` is assigned to but never used")
+            }
+            CheckKind::UselessObjectInheritance(name) => {
+                format!("Class `{name}` inherits from object")
+            }
+            CheckKind::YieldOutsideFunction => {
+                "a `yield` or `yield from` statement outside of a function/method".to_string()
+            }
         }
     }
+
+    /// Whether the check kind is (potentially) fixable.
+    pub fn fixable(&self) -> bool {
+        matches!(
+            self,
+            CheckKind::NoAssertEquals | CheckKind::UselessObjectInheritance(_)
+        )
+    }
 }
 
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Fix {
+    pub content: String,
+    pub start: Location,
+    pub end: Location,
+    pub applied: bool,
+}
+
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct Check {
     pub kind: CheckKind,
     pub location: Location,
+    pub fix: Option<Fix>,
 }
 
+static NO_QA_REGEX: Lazy<Regex> = Lazy::new(|| {
+    Regex::new(r"(?i)# noqa(?::\s?(?P<codes>([A-Z]+[0-9]+(?:[,\s]+)?)+))?").expect("Invalid regex")
+});
+static SPLIT_COMMA_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"[,\s]").expect("Invalid regex"));
+
 impl Check {
+    pub fn new(kind: CheckKind, location: Location) -> Self {
+        Self {
+            kind,
+            location,
+            fix: None,
+        }
+    }
+
+    pub fn amend(&mut self, fix: Fix) {
+        self.fix = Some(fix);
+    }
+
     pub fn is_inline_ignored(&self, line: &str) -> bool {
-        let re = Regex::new(r"(?i)# noqa(?::\s?(?P<codes>([A-Z]+[0-9]+(?:[,\s]+)?)+))?").unwrap();
-        match re.captures(line) {
+        match NO_QA_REGEX.captures(line) {
             Some(caps) => match caps.name("codes") {
                 Some(codes) => {
-                    let re = Regex::new(r"[,\s]").unwrap();
-                    for code in re
+                    for code in SPLIT_COMMA_REGEX
                         .split(codes.as_str())
                         .map(|code| code.trim())
                         .filter(|code| !code.is_empty())

src/fs.rs

@@ -1,43 +0,0 @@
-use std::fs::File;
-use std::io::{BufReader, Read};
-use std::path::{Path, PathBuf};
-
-use anyhow::Result;
-use glob::Pattern;
-use walkdir::{DirEntry, WalkDir};
-
-fn is_not_hidden(entry: &DirEntry) -> bool {
-    entry
-        .file_name()
-        .to_str()
-        .map(|s| (entry.depth() == 0 || !s.starts_with('.')))
-        .unwrap_or(false)
-}
-
-fn is_not_excluded(entry: &DirEntry, exclude: &[Pattern]) -> bool {
-    entry
-        .path()
-        .to_str()
-        .map(|s| !exclude.iter().any(|pattern| pattern.matches(s)))
-        .unwrap_or(false)
-}
-
-pub fn iter_python_files<'a>(
-    path: &'a PathBuf,
-    exclude: &'a [Pattern],
-) -> impl Iterator<Item = DirEntry> + 'a {
-    WalkDir::new(path)
-        .follow_links(true)
-        .into_iter()
-        .filter_entry(|entry| is_not_hidden(entry) && is_not_excluded(entry, exclude))
-        .filter_map(|entry| entry.ok())
-        .filter(|entry| entry.path().to_string_lossy().ends_with(".py"))
-}
-
-pub fn read_file(path: &Path) -> Result<String> {
-    let file = File::open(path)?;
-    let mut buf_reader = BufReader::new(file);
-    let mut contents = String::new();
-    buf_reader.read_to_string(&mut contents)?;
-    Ok(contents)
-}

src/lib.rs

@@ -1,12 +1,73 @@
-mod builtins;
-mod cache;
+use rustpython_parser::ast::Location;
+use std::path::Path;
+
+use rustpython_parser::parser;
+use wasm_bindgen::prelude::*;
+
+use crate::check_ast::check_ast;
+use crate::check_lines::check_lines;
+use crate::checks::{Check, CheckCode, CheckKind, ALL_CHECK_CODES};
+use crate::settings::Settings;
+
+mod ast;
+mod autofix;
 pub mod check_ast;
 mod check_lines;
 pub mod checks;
-pub mod fs;
-pub mod linter;
-pub mod logging;
-pub mod message;
-mod pyproject;
+mod python;
 pub mod settings;
-mod visitor;
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+struct Message {
+    code: CheckCode,
+    message: String,
+    location: Location,
+}
+
+#[wasm_bindgen]
+extern "C" {
+    pub fn alert(s: &str);
+}
+
+#[wasm_bindgen]
+pub fn check(contents: &str) -> String {
+    let settings = Settings::for_rules(ALL_CHECK_CODES.to_vec());
+    let autofix = autofix::fixer::Mode::None;
+
+    // Aggregate all checks.
+    let mut checks: Vec<Check> = vec![];
+
+    // Run the AST-based checks.
+    match parser::parse_program(contents, "<filename>") {
+        Ok(python_ast) => checks.extend(check_ast(
+            &python_ast,
+            contents,
+            &settings,
+            &autofix,
+            Path::new("<filename>"),
+        )),
+        Err(parse_error) => {
+            if settings.select.contains(&CheckCode::E999) {
+                checks.push(Check::new(
+                    CheckKind::SyntaxError(parse_error.error.to_string()),
+                    parse_error.location,
+                ))
+            }
+        }
+    }
+
+    // Run the lines-based checks.
+    check_lines(&mut checks, contents, &settings);
+
+    let messages: Vec<Message> = checks
+        .into_iter()
+        .map(|check| Message {
+            code: check.kind.code().clone(),
+            message: check.kind.body(),
+            location: check.location,
+        })
+        .collect();
+
+    serde_json::to_string(&messages).unwrap()
+}

src/linter.rs

@@ -1,454 +0,0 @@
-use std::path::Path;
-
-use anyhow::Result;
-use log::debug;
-use rustpython_parser::parser;
-
-use crate::check_ast::check_ast;
-use crate::check_lines::check_lines;
-use crate::checks::{Check, LintSource};
-use crate::message::Message;
-use crate::settings::Settings;
-use crate::{cache, fs};
-
-pub fn check_path(path: &Path, settings: &Settings, mode: &cache::Mode) -> Result<Vec<Message>> {
-    // Check the cache.
-    if let Some(messages) = cache::get(path, settings, mode) {
-        debug!("Cache hit for: {}", path.to_string_lossy());
-        return Ok(messages);
-    }
-
-    // Read the file from disk.
-    let contents = fs::read_file(path)?;
-
-    // Aggregate all checks.
-    let mut checks: Vec<Check> = vec![];
-
-    // Run the AST-based checks.
-    if settings
-        .select
-        .iter()
-        .any(|check_code| matches!(check_code.lint_source(), LintSource::AST))
-    {
-        let path = path.to_string_lossy();
-        let python_ast = parser::parse_program(&contents, &path)?;
-        checks.extend(check_ast(&python_ast, settings, &path));
-    }
-
-    // Run the lines-based checks.
-    check_lines(&mut checks, &contents, settings);
-
-    // Convert to messages.
-    let messages: Vec<Message> = checks
-        .into_iter()
-        .map(|check| Message {
-            kind: check.kind,
-            location: check.location,
-            filename: path.to_string_lossy().to_string(),
-        })
-        .collect();
-    cache::set(path, settings, &messages, mode);
-
-    Ok(messages)
-}
-
-#[cfg(test)]
-mod tests {
-    use std::collections::BTreeSet;
-    use std::path::Path;
-
-    use anyhow::Result;
-    use rustpython_parser::ast::Location;
-
-    use crate::checks::{CheckCode, CheckKind};
-    use crate::linter::check_path;
-    use crate::message::Message;
-    use crate::{cache, settings};
-
-    #[test]
-    fn e501() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/E501.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::E501]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![Message {
-            kind: CheckKind::LineTooLong,
-            location: Location::new(5, 89),
-            filename: "./resources/test/src/E501.py".to_string(),
-        }];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f401() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F401.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F401]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::UnusedImport("logging.handlers".to_string()),
-                location: Location::new(11, 1),
-                filename: "./resources/test/src/F401.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::UnusedImport("functools".to_string()),
-                location: Location::new(2, 1),
-                filename: "./resources/test/src/F401.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::UnusedImport("collections.OrderedDict".to_string()),
-                location: Location::new(3, 1),
-                filename: "./resources/test/src/F401.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f403() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F403.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F403]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::ImportStarUsage,
-                location: Location::new(1, 1),
-                filename: "./resources/test/src/F403.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::ImportStarUsage,
-                location: Location::new(2, 1),
-                filename: "./resources/test/src/F403.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-    #[test]
-    fn f541() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F541.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F541]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::FStringMissingPlaceholders,
-                location: Location::new(4, 7),
-                filename: "./resources/test/src/F541.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::FStringMissingPlaceholders,
-                location: Location::new(5, 7),
-                filename: "./resources/test/src/F541.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::FStringMissingPlaceholders,
-                location: Location::new(7, 7),
-                filename: "./resources/test/src/F541.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f634() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F634.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F634]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::IfTuple,
-                location: Location::new(1, 1),
-                filename: "./resources/test/src/F634.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::IfTuple,
-                location: Location::new(7, 5),
-                filename: "./resources/test/src/F634.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f704() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F704.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F704]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::YieldOutsideFunction,
-                location: Location::new(6, 5),
-                filename: "./resources/test/src/F704.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::YieldOutsideFunction,
-                location: Location::new(9, 1),
-                filename: "./resources/test/src/F704.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::YieldOutsideFunction,
-                location: Location::new(10, 1),
-                filename: "./resources/test/src/F704.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f706() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F706.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F706]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::ReturnOutsideFunction,
-                location: Location::new(6, 5),
-                filename: "./resources/test/src/F706.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::ReturnOutsideFunction,
-                location: Location::new(9, 1),
-                filename: "./resources/test/src/F706.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f821() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F821.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F821]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::UndefinedName("self".to_string()),
-                location: Location::new(2, 12),
-                filename: "./resources/test/src/F821.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::UndefinedName("self".to_string()),
-                location: Location::new(6, 13),
-                filename: "./resources/test/src/F821.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::UndefinedName("self".to_string()),
-                location: Location::new(10, 9),
-                filename: "./resources/test/src/F821.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::UndefinedName("numeric_string".to_string()),
-                location: Location::new(21, 12),
-                filename: "./resources/test/src/F821.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f831() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F831.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F831]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::DuplicateArgumentName,
-                location: Location::new(1, 25),
-                filename: "./resources/test/src/F831.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::DuplicateArgumentName,
-                location: Location::new(5, 28),
-                filename: "./resources/test/src/F831.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::DuplicateArgumentName,
-                location: Location::new(9, 27),
-                filename: "./resources/test/src/F831.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f832() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F832.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F832]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![Message {
-            kind: CheckKind::UndefinedLocal("my_var".to_string()),
-            location: Location::new(6, 5),
-            filename: "./resources/test/src/F832.py".to_string(),
-        }];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f841() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F841.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F841]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::UnusedVariable("e".to_string()),
-                location: Location::new(3, 1),
-                filename: "./resources/test/src/F841.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::UnusedVariable("z".to_string()),
-                location: Location::new(16, 5),
-                filename: "./resources/test/src/F841.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-
-    #[test]
-    fn f901() -> Result<()> {
-        let actual = check_path(
-            &Path::new("./resources/test/src/F901.py"),
-            &settings::Settings {
-                line_length: 88,
-                exclude: vec![],
-                select: BTreeSet::from([CheckCode::F901]),
-            },
-            &cache::Mode::None,
-        )?;
-        let expected = vec![
-            Message {
-                kind: CheckKind::RaiseNotImplemented,
-                location: Location::new(2, 5),
-                filename: "./resources/test/src/F901.py".to_string(),
-            },
-            Message {
-                kind: CheckKind::RaiseNotImplemented,
-                location: Location::new(6, 5),
-                filename: "./resources/test/src/F901.py".to_string(),
-            },
-        ];
-        assert_eq!(actual.len(), expected.len());
-        for i in 0..actual.len() {
-            assert_eq!(actual[i], expected[i]);
-        }
-
-        Ok(())
-    }
-}