Formatting

crates/ruff_linter/src/rules/pylint/mod.rs

@@ -77,7 +77,10 @@ mod tests {
     #[test_case(Rule::InvalidAllFormat, Path::new("invalid_all_format.py"))]
     #[test_case(Rule::InvalidAllObject, Path::new("invalid_all_object.py"))]
     #[test_case(Rule::InvalidBoolReturnType, Path::new("invalid_return_type_bool.py"))]
-    #[test_case(Rule::InvalidLengthReturnType, Path::new("invalid_return_type_length.py"))]
+    #[test_case(
+        Rule::InvalidLengthReturnType,
+        Path::new("invalid_return_type_length.py")
+    )]
     #[test_case(Rule::InvalidStrReturnType, Path::new("invalid_return_type_str.py"))]
     #[test_case(Rule::DuplicateBases, Path::new("duplicate_bases.py"))]
     #[test_case(Rule::InvalidCharacterBackspace, Path::new("invalid_characters.py"))]

crates/ruff_linter/src/rules/pylint/rules/invalid_length_return.rs

@@ -32,7 +32,6 @@ use crate::checkers::ast::Checker;
 /// Note: Strictly speaking `bool` is a subclass of `int`, thus returning `True`/`False` is valid.
 /// To be consistent with other rules (e.g. PLE0305 invalid-index-returned), ruff will raise, compared
 /// to pylint which will not raise.
-/// 
 /// ## References
 /// - [Python documentation: The `__len__` method](https://docs.python.org/3/reference/datamodel.html#object.__len__)
 #[violation]
@@ -67,7 +66,8 @@ pub(crate) fn invalid_length_return(checker: &mut Checker, name: &str, body: &[S
                 ResolvedPythonType::from(value),
                 ResolvedPythonType::Unknown
                     | ResolvedPythonType::Atom(PythonType::Number(NumberLike::Integer))
-            ) || is_negative_integer(value) {
+            ) || is_negative_integer(value)
+            {
                 checker
                     .diagnostics
                     .push(Diagnostic::new(InvalidLengthReturnType, value.range()));
@@ -82,9 +82,8 @@ pub(crate) fn invalid_length_return(checker: &mut Checker, name: &str, body: &[S
 }
 
 fn is_negative_integer(value: &Expr) -> bool {
-    let Expr::UnaryOp(ast::ExprUnaryOp { op, .. }) = value else { return false; };
-    match op {
-        ast::UnaryOp::USub => true,
-        _ => false,
-    }
+    let Expr::UnaryOp(ast::ExprUnaryOp { op, .. }) = value else {
+        return false;
+    };
+    matches!(op, ast::UnaryOp::USub)
 }

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLE0303_invalid_return_type_length.py.snap

@@ -30,3 +30,13 @@ invalid_return_type_length.py:13:16: PLE0303 `__len__` does not return a non-neg
 14 | 
 15 | class LengthNegative:
    |
+
+invalid_return_type_length.py:17:16: PLE0303 `__len__` does not return a non-negative `integer`
+   |
+15 | class LengthNegative:
+16 |     def __len__(self):
+17 |         return -42  # [invalid-length-return]
+   |                ^^^ PLE0303
+18 | 
+19 | # TODO: Once Ruff has better type checking
+   |