[flake8-pytest-style] Do not emit diagnostics for empty for loops (PT012, PT031)

crates/ruff_linter/resources/test/fixtures/flake8_pytest_style/PT012.py

@@ -73,3 +73,44 @@ def test_error_try():
             [].size
         except:
             raise
+
+
+# https://github.com/astral-sh/ruff/issues/9730
+def test_for_loops():
+
+    ## Errors
+
+    with pytest.raises(RuntimeError):
+        for a in b:
+            print()
+
+    with pytest.raises(RuntimeError):
+        for a in b:
+            assert foo
+
+    with pytest.raises(RuntimeError):
+        async for a in b:
+            print()
+
+    with pytest.raises(RuntimeError):
+        async for a in b:
+            assert foo
+
+
+    ## No errors in preview
+
+    with pytest.raises(RuntimeError):
+        for a in b:
+            pass
+
+    with pytest.raises(RuntimeError):
+        for a in b:
+            ...
+
+    with pytest.raises(RuntimeError):
+        async for a in b:
+            pass
+
+    with pytest.raises(RuntimeError):
+        async for a in b:
+            ...

crates/ruff_linter/resources/test/fixtures/flake8_pytest_style/PT031.py

@@ -73,3 +73,44 @@ def test_error_try():
             foo()
         except:
             raise
+
+
+# https://github.com/astral-sh/ruff/issues/9730
+def test_for_loops():
+
+    ## Errors
+
+    with pytest.warns(RuntimeError):
+        for a in b:
+            print()
+
+    with pytest.warns(RuntimeError):
+        for a in b:
+            assert foo
+
+    with pytest.warns(RuntimeError):
+        async for a in b:
+            print()
+
+    with pytest.warns(RuntimeError):
+        async for a in b:
+            assert foo
+
+
+    ## No errors in preview
+
+    with pytest.warns(RuntimeError):
+        for a in b:
+            pass
+
+    with pytest.warns(RuntimeError):
+        for a in b:
+            ...
+
+    with pytest.warns(RuntimeError):
+        async for a in b:
+            pass
+
+    with pytest.warns(RuntimeError):
+        async for a in b:
+            ...

crates/ruff_linter/src/rules/flake8_pytest_style/mod.rs

@@ -11,7 +11,7 @@ mod tests {
     use test_case::test_case;
 
     use crate::registry::Rule;
-    use crate::settings::types::IdentifierPattern;
+    use crate::settings::types::{IdentifierPattern, PreviewMode};
     use crate::test::test_path;
     use crate::{assert_messages, settings};
 
@@ -358,6 +358,36 @@ mod tests {
         Ok(())
     }
 
+    #[test_case(
+        Rule::PytestRaisesWithMultipleStatements,
+        Path::new("PT012.py"),
+        Settings::default(),
+        "PT012_preview"
+    )]
+    #[test_case(
+        Rule::PytestWarnsWithMultipleStatements,
+        Path::new("PT031.py"),
+        Settings::default(),
+        "PT031_preview"
+    )]
+    fn test_pytest_style_preview(
+        rule_code: Rule,
+        path: &Path,
+        plugin_settings: Settings,
+        name: &str,
+    ) -> Result<()> {
+        let diagnostics = test_path(
+            Path::new("flake8_pytest_style").join(path).as_path(),
+            &settings::LinterSettings {
+                preview: PreviewMode::Enabled,
+                flake8_pytest_style: plugin_settings,
+                ..settings::LinterSettings::for_rule(rule_code)
+            },
+        )?;
+        assert_messages!(name, diagnostics);
+        Ok(())
+    }
+
     /// This test ensure that PT006 and PT007 don't conflict when both of them suggest a fix that
     /// edits `argvalues` for `pytest.mark.parametrize`.
     #[test]

crates/ruff_linter/src/rules/flake8_pytest_style/rules/raises.rs

@@ -20,6 +20,10 @@ use super::helpers::is_empty_or_null_string;
 /// A `pytest.raises` context manager should only contain a single simple
 /// statement that raises the expected exception.
 ///
+/// In [preview], this rule allows `pytest.raises` bodies to contain `for`
+/// loops with empty bodies (e.g., `pass` or `...` statements), to test
+/// iterator behavior.
+///
 /// ## Example
 /// ```python
 /// import pytest
@@ -46,6 +50,8 @@ use super::helpers::is_empty_or_null_string;
 ///
 /// ## References
 /// - [`pytest` documentation: `pytest.raises`](https://docs.pytest.org/en/latest/reference/reference.html#pytest-raises)
+///
+/// [preview]: https://docs.astral.sh/ruff/preview/
 #[derive(ViolationMetadata)]
 pub(crate) struct PytestRaisesWithMultipleStatements;
 
@@ -205,10 +211,18 @@ pub(crate) fn complex_raises(
     // Check body for `pytest.raises` context manager
     if raises_called {
         let is_too_complex = if let [stmt] = body {
+            let in_preview = checker.settings.preview.is_enabled();
+
             match stmt {
                 Stmt::With(ast::StmtWith { body, .. }) => is_non_trivial_with_body(body),
-                // Allow function and class definitions to test decorators
+                // Allow function and class definitions to test decorators.
                 Stmt::ClassDef(_) | Stmt::FunctionDef(_) => false,
+                // Allow empty `for` loops to test iterators.
+                Stmt::For(ast::StmtFor { body, .. }) if in_preview => match &body[..] {
+                    [Stmt::Pass(_)] => false,
+                    [Stmt::Expr(ast::StmtExpr { value, .. })] => !value.is_ellipsis_literal_expr(),
+                    _ => true,
+                },
                 stmt => is_compound_statement(stmt),
             }
         } else {

crates/ruff_linter/src/rules/flake8_pytest_style/rules/warns.rs

@@ -20,6 +20,10 @@ use super::helpers::is_empty_or_null_string;
 /// A `pytest.warns` context manager should only contain a single
 /// simple statement that triggers the expected warning.
 ///
+/// In [preview], this rule allows `pytest.warns` bodies to contain `for`
+/// loops with empty bodies (e.g., `pass` or `...` statements), to test
+/// iterator behavior.
+///
 /// ## Example
 /// ```python
 /// import pytest
@@ -38,12 +42,14 @@ use super::helpers::is_empty_or_null_string;
 ///
 /// def test_foo_warns():
 ///     setup()
-///     with pytest.warning(Warning):
+///     with pytest.warns(Warning):
 ///         foo()
 /// ```
 ///
 /// ## References
 /// - [`pytest` documentation: `pytest.warns`](https://docs.pytest.org/en/latest/reference/reference.html#pytest-warns)
+///
+/// [preview]: https://docs.astral.sh/ruff/preview/
 #[derive(ViolationMetadata)]
 pub(crate) struct PytestWarnsWithMultipleStatements;
 
@@ -200,10 +206,18 @@ pub(crate) fn complex_warns(checker: &mut Checker, stmt: &Stmt, items: &[WithIte
     // Check body for `pytest.warns` context manager
     if warns_called {
         let is_too_complex = if let [stmt] = body {
+            let in_preview = checker.settings.preview.is_enabled();
+
             match stmt {
                 Stmt::With(ast::StmtWith { body, .. }) => is_non_trivial_with_body(body),
-                // Allow function and class definitions to test decorators
+                // Allow function and class definitions to test decorators.
                 Stmt::ClassDef(_) | Stmt::FunctionDef(_) => false,
+                // Allow empty `for` loops to test iterators.
+                Stmt::For(ast::StmtFor { body, .. }) if in_preview => match &body[..] {
+                    [Stmt::Pass(_)] => false,
+                    [Stmt::Expr(ast::StmtExpr { value, .. })] => !value.is_ellipsis_literal_expr(),
+                    _ => true,
+                },
                 stmt => is_compound_statement(stmt),
             }
         } else {

crates/ruff_linter/src/rules/flake8_pytest_style/snapshots/ruff_linter__rules__flake8_pytest_style__tests__PT012.snap

@@ -78,3 +78,95 @@ PT012.py:71:5: PT012 `pytest.raises()` block should contain a single simple stat
 75 | |             raise
    | |_________________^ PT012
    |
+
+PT012.py:83:5: PT012 `pytest.raises()` block should contain a single simple statement
+   |
+81 |       ## Errors
+82 |
+83 | /     with pytest.raises(RuntimeError):
+84 | |         for a in b:
+85 | |             print()
+   | |___________________^ PT012
+86 |
+87 |       with pytest.raises(RuntimeError):
+   |
+
+PT012.py:87:5: PT012 `pytest.raises()` block should contain a single simple statement
+   |
+85 |               print()
+86 |
+87 | /     with pytest.raises(RuntimeError):
+88 | |         for a in b:
+89 | |             assert foo
+   | |______________________^ PT012
+90 |
+91 |       with pytest.raises(RuntimeError):
+   |
+
+PT012.py:91:5: PT012 `pytest.raises()` block should contain a single simple statement
+   |
+89 |               assert foo
+90 |
+91 | /     with pytest.raises(RuntimeError):
+92 | |         async for a in b:
+93 | |             print()
+   | |___________________^ PT012
+94 |
+95 |       with pytest.raises(RuntimeError):
+   |
+
+PT012.py:95:5: PT012 `pytest.raises()` block should contain a single simple statement
+   |
+93 |               print()
+94 |
+95 | /     with pytest.raises(RuntimeError):
+96 | |         async for a in b:
+97 | |             assert foo
+   | |______________________^ PT012
+   |
+
+PT012.py:102:5: PT012 `pytest.raises()` block should contain a single simple statement
+    |
+100 |       ## No errors in preview
+101 |
+102 | /     with pytest.raises(RuntimeError):
+103 | |         for a in b:
+104 | |             pass
+    | |________________^ PT012
+105 |
+106 |       with pytest.raises(RuntimeError):
+    |
+
+PT012.py:106:5: PT012 `pytest.raises()` block should contain a single simple statement
+    |
+104 |               pass
+105 |
+106 | /     with pytest.raises(RuntimeError):
+107 | |         for a in b:
+108 | |             ...
+    | |_______________^ PT012
+109 |
+110 |       with pytest.raises(RuntimeError):
+    |
+
+PT012.py:110:5: PT012 `pytest.raises()` block should contain a single simple statement
+    |
+108 |               ...
+109 |
+110 | /     with pytest.raises(RuntimeError):
+111 | |         async for a in b:
+112 | |             pass
+    | |________________^ PT012
+113 |
+114 |       with pytest.raises(RuntimeError):
+    |
+
+PT012.py:114:5: PT012 `pytest.raises()` block should contain a single simple statement
+    |
+112 |               pass
+113 |
+114 | /     with pytest.raises(RuntimeError):
+115 | |         async for a in b:
+116 | |             ...
+    | |_______________^ PT012
+    |