Stabilize pytest-raises-ambiguous-pattern (RUF043) (#20253)

This one has been a bit contentious in the past. It usually uncovers
~700 ecosystem hits. See:

- https://github.com/astral-sh/ruff/pull/16657
- https://github.com/astral-sh/ruff/issues/16690

But I think there's consensus that it's okay to merge as-is. We'd love
an
autofix since it's so common, but we can't reliably tell what a user
meant. The
pattern is ambiguous after all 😆

This is the first rule that actually needed its test case relocated, but
the
docs looked good.

crates/ruff_linter/src/codes.rs

@@ -1032,7 +1032,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Ruff, "039") => (RuleGroup::Preview, rules::ruff::rules::UnrawRePattern),
         (Ruff, "040") => (RuleGroup::Stable, rules::ruff::rules::InvalidAssertMessageLiteralArgument),
         (Ruff, "041") => (RuleGroup::Stable, rules::ruff::rules::UnnecessaryNestedLiteral),
-        (Ruff, "043") => (RuleGroup::Preview, rules::ruff::rules::PytestRaisesAmbiguousPattern),
+        (Ruff, "043") => (RuleGroup::Stable, rules::ruff::rules::PytestRaisesAmbiguousPattern),
         (Ruff, "045") => (RuleGroup::Preview, rules::ruff::rules::ImplicitClassVarInDataclass),
         (Ruff, "046") => (RuleGroup::Stable, rules::ruff::rules::UnnecessaryCastToInt),
         (Ruff, "047") => (RuleGroup::Preview, rules::ruff::rules::NeedlessElse),

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

@@ -85,6 +85,7 @@ mod tests {
     #[test_case(Rule::InvalidAssertMessageLiteralArgument, Path::new("RUF040.py"))]
     #[test_case(Rule::UnnecessaryNestedLiteral, Path::new("RUF041.py"))]
     #[test_case(Rule::UnnecessaryNestedLiteral, Path::new("RUF041.pyi"))]
+    #[test_case(Rule::PytestRaisesAmbiguousPattern, Path::new("RUF043.py"))]
     #[test_case(Rule::UnnecessaryCastToInt, Path::new("RUF046.py"))]
     #[test_case(Rule::UnnecessaryCastToInt, Path::new("RUF046_CR.py"))]
     #[test_case(Rule::UnnecessaryCastToInt, Path::new("RUF046_LF.py"))]
@@ -535,7 +536,6 @@ mod tests {
     #[test_case(Rule::UnnecessaryRegularExpression, Path::new("RUF055_1.py"))]
     #[test_case(Rule::UnnecessaryRegularExpression, Path::new("RUF055_2.py"))]
     #[test_case(Rule::UnnecessaryRegularExpression, Path::new("RUF055_3.py"))]
-    #[test_case(Rule::PytestRaisesAmbiguousPattern, Path::new("RUF043.py"))]
     #[test_case(Rule::IndentedFormFeed, Path::new("RUF054.py"))]
     #[test_case(Rule::ImplicitClassVarInDataclass, Path::new("RUF045.py"))]
     fn preview_rules(rule_code: Rule, path: &Path) -> Result<()> {

crates/ruff_linter/src/rules/ruff/rules/pytest_raises_ambiguous_pattern.rs

@@ -27,7 +27,8 @@ use crate::rules::flake8_pytest_style::rules::is_pytest_raises;
 ///     do_thing_that_raises()
 /// ```
 ///
-/// Use instead:
+/// If the pattern is intended to be a regular expression, use a raw string to signal this
+/// intention:
 ///
 /// ```python
 /// import pytest
@@ -37,7 +38,7 @@ use crate::rules::flake8_pytest_style::rules::is_pytest_raises;
 ///     do_thing_that_raises()
 /// ```
 ///
-/// Alternatively:
+/// Alternatively, escape any regex metacharacters with `re.escape`:
 ///
 /// ```python
 /// import pytest
@@ -48,7 +49,7 @@ use crate::rules::flake8_pytest_style::rules::is_pytest_raises;
 ///     do_thing_that_raises()
 /// ```
 ///
-/// or:
+/// or directly with backslashes:
 ///
 /// ```python
 /// import pytest