[pycodestyle] Exempt pytest.importorskip() calls (E402) (#14474)

## Summary

Resolves #13537.

## Test Plan

`cargo nextest run` and `cargo insta test`.

crates/ruff_linter/resources/test/fixtures/pycodestyle/E402_3.py

@@ -0,0 +1,8 @@
+import pytest
+
+pytest.importorskip("foo.bar")
+
+import re
+from sys import version
+
+from numpy import *

crates/ruff_linter/src/checkers/ast/mod.rs

@@ -453,6 +453,8 @@ impl<'a> Checker<'a> {
 
 impl<'a> Visitor<'a> for Checker<'a> {
     fn visit_stmt(&mut self, stmt: &'a Stmt) {
+        let in_preview = self.settings.preview.is_enabled();
+
         // Step 0: Pre-processing
         self.semantic.push_node(stmt);
 
@@ -504,7 +506,8 @@ impl<'a> Visitor<'a> for Checker<'a> {
                     || helpers::in_nested_block(self.semantic.current_statements())
                     || imports::is_matplotlib_activation(stmt, self.semantic())
                     || imports::is_sys_path_modification(stmt, self.semantic())
-                    || imports::is_os_environ_modification(stmt, self.semantic()))
+                    || imports::is_os_environ_modification(stmt, self.semantic())
+                    || (in_preview && imports::is_pytest_importorskip(stmt, self.semantic())))
                 {
                     self.semantic.flags |= SemanticModelFlags::IMPORT_BOUNDARY;
                 }

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

@@ -72,14 +72,15 @@ mod tests {
         Ok(())
     }
 
+    #[test_case(Rule::ModuleImportNotAtTopOfFile, Path::new("E402_3.py"))]
     #[test_case(Rule::RedundantBackslash, Path::new("E502.py"))]
+    // E741 has different behaviour for `.pyi` files in preview mode
+    #[test_case(Rule::AmbiguousVariableName, Path::new("E741.pyi"))]
     #[test_case(Rule::TooManyNewlinesAtEndOfFile, Path::new("W391_0.py"))]
     #[test_case(Rule::TooManyNewlinesAtEndOfFile, Path::new("W391_1.py"))]
     #[test_case(Rule::TooManyNewlinesAtEndOfFile, Path::new("W391_2.py"))]
     #[test_case(Rule::TooManyNewlinesAtEndOfFile, Path::new("W391_3.py"))]
     #[test_case(Rule::TooManyNewlinesAtEndOfFile, Path::new("W391_4.py"))]
-    // E741 has different behaviour for `.pyi` files in preview mode
-    #[test_case(Rule::AmbiguousVariableName, Path::new("E741.pyi"))]
     fn preview_rules(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!(
             "preview__{}_{}",

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__preview__E402_E402_3.py.snap

@@ -0,0 +1,5 @@
+---
+source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
+snapshot_kind: text
+---
+

crates/ruff_python_semantic/src/analyze/imports.rs

@@ -102,3 +102,24 @@ pub fn is_matplotlib_activation(stmt: &Stmt, semantic: &SemanticModel) -> bool {
         .resolve_qualified_name(func.as_ref())
         .is_some_and(|qualified_name| matches!(qualified_name.segments(), ["matplotlib", "use"]))
 }
+
+/// Returns `true` if a [`Stmt`] is a `pytest.importorskip()` call, as in:
+/// ```python
+/// import pytest
+///
+/// pytest.importorskip("foo.bar")
+/// ```
+pub fn is_pytest_importorskip(stmt: &Stmt, semantic: &SemanticModel) -> bool {
+    let Stmt::Expr(ast::StmtExpr { value, .. }) = stmt else {
+        return false;
+    };
+    let Expr::Call(ast::ExprCall { func, .. }) = value.as_ref() else {
+        return false;
+    };
+
+    semantic
+        .resolve_qualified_name(func.as_ref())
+        .is_some_and(|qualified_name| {
+            matches!(qualified_name.segments(), ["pytest", "importorskip"])
+        })
+}