Base INP check on package inference (#2079)

If a file doesn't have a `package`, then it must both be in a directory that lacks an `__init__.py`, and a directory that _isn't_ marked as a namespace package.

Closes #2075.

src/checkers/filesystem.rs

@@ -4,12 +4,16 @@ use crate::registry::{Diagnostic, Rule};
 use crate::rules::flake8_no_pep420::rules::implicit_namespace_package;
 use crate::settings::Settings;
 
-pub fn check_file_path(path: &Path, settings: &Settings) -> Vec<Diagnostic> {
+pub fn check_file_path(
+    path: &Path,
+    package: Option<&Path>,
+    settings: &Settings,
+) -> Vec<Diagnostic> {
     let mut diagnostics: Vec<Diagnostic> = vec![];
 
     // flake8-no-pep420
     if settings.rules.enabled(&Rule::ImplicitNamespacePackage) {
-        if let Some(diagnostic) = implicit_namespace_package(path) {
+        if let Some(diagnostic) = implicit_namespace_package(path, package) {
             diagnostics.push(diagnostic);
         }
     }

src/linter.rs

@@ -16,6 +16,8 @@ use crate::directives::Directives;
 use crate::doc_lines::{doc_lines_from_ast, doc_lines_from_tokens};
 use crate::message::{Message, Source};
 use crate::noqa::add_noqa;
+#[cfg(test)]
+use crate::packaging::detect_package_root;
 use crate::registry::{Diagnostic, LintSource, Rule};
 use crate::settings::{flags, Settings};
 use crate::source_code::{Indexer, Locator, Stylist};
@@ -69,7 +71,7 @@ pub fn check_path(
         .iter_enabled()
         .any(|rule_code| matches!(rule_code.lint_source(), LintSource::Filesystem))
     {
-        diagnostics.extend(check_file_path(path, settings));
+        diagnostics.extend(check_file_path(path, package, settings));
     }
 
     // Run the AST-based rules.
@@ -395,7 +397,8 @@ pub fn test_path(path: &Path, settings: &Settings) -> Result<Vec<Diagnostic>> {
         directives::extract_directives(&tokens, directives::Flags::from_settings(settings));
     let mut diagnostics = check_path(
         path,
-        None,
+        path.parent()
+            .and_then(|parent| detect_package_root(parent, &settings.namespace_packages)),
         &contents,
         tokens,
         &locator,

src/rules/flake8_no_pep420/mod.rs

@@ -3,7 +3,7 @@ pub(crate) mod rules;
 
 #[cfg(test)]
 mod tests {
-    use std::path::Path;
+    use std::path::{Path, PathBuf};
 
     use anyhow::Result;
     use test_case::test_case;
@@ -12,11 +12,12 @@ mod tests {
     use crate::registry::Rule;
     use crate::settings::Settings;
 
-    #[test_case(Path::new("test_pass"); "INP001_0")]
+    #[test_case(Path::new("test_pass_init"); "INP001_0")]
     #[test_case(Path::new("test_fail_empty"); "INP001_1")]
     #[test_case(Path::new("test_fail_nonempty"); "INP001_2")]
     #[test_case(Path::new("test_fail_shebang"); "INP001_3")]
     #[test_case(Path::new("test_ignored"); "INP001_4")]
+    #[test_case(Path::new("test_pass_namespace_package"); "INP001_5")]
     fn test_flake8_no_pep420(path: &Path) -> Result<()> {
         let snapshot = format!("{}", path.to_string_lossy());
         let diagnostics = test_path(
@@ -24,7 +25,12 @@ mod tests {
                 .join(path)
                 .join("example.py")
                 .as_path(),
-            &Settings::for_rule(Rule::ImplicitNamespacePackage),
+            &Settings {
+                namespace_packages: vec![PathBuf::from(
+                    "./resources/test/fixtures/flake8_no_pep420/test_pass_namespace_package",
+                )],
+                ..Settings::for_rule(Rule::ImplicitNamespacePackage)
+            },
         )?;
         insta::assert_yaml_snapshot!(snapshot, diagnostics);
         Ok(())

src/rules/flake8_no_pep420/rules.rs

@@ -5,14 +5,13 @@ use crate::registry::Diagnostic;
 use crate::{fs, violations};
 
 /// INP001
-pub fn implicit_namespace_package(path: &Path) -> Option<Diagnostic> {
-    if let Some(parent) = path.parent() {
-        if !parent.join("__init__.py").as_path().exists() {
-            return Some(Diagnostic::new(
-                violations::ImplicitNamespacePackage(fs::relativize_path(path).to_string()),
-                Range::default(),
-            ));
-        }
+pub fn implicit_namespace_package(path: &Path, package: Option<&Path>) -> Option<Diagnostic> {
+    if package.is_none() {
+        Some(Diagnostic::new(
+            violations::ImplicitNamespacePackage(fs::relativize_path(path).to_string()),
+            Range::default(),
+        ))
+    } else {
+        None
     }
-    None
 }

src/rules/flake8_no_pep420/snapshots/ruff__rules__flake8_no_pep420__tests__test_pass_namespace_package.snap

@@ -0,0 +1,6 @@
+---
+source: src/rules/flake8_no_pep420/mod.rs
+expression: diagnostics
+---
+[]
+