Exclude companion declarations of the requesting fixture

Summary:
A fixture's implementation and stub describe the same provider. Use retained module-owned fixture metadata to recognize a same-name parent request and exclude that provider's companion declaration before climbing to an ancestor. Preserve class-to-module parents and ordinary consumers' implementation/stub preference without resolving unrelated imports.

___

landed-with-radar-review

Differential Revision: D129132931

fbshipit-source-id: fb3076c3ce74c4b5708d3c6b09dce29a518a747d

Author: stroxler

pyrefly/lib/state/lsp/pytest.rs

@@ -132,6 +132,16 @@ impl<'a> Transaction<'a> {
             })
             .collect();
         if definitions.is_empty() && preference.follow_pytest_conftest {
+            let requesting_fixture_name = self
+                .get_exports_data(handle)
+                .pytest_fixtures()
+                .iter()
+                .find(|fixture| {
+                    fixture.range == enclosing_function_range
+                        && fixture.fixture_name.as_ref().unwrap_or(&fixture.name) == identifier.id()
+                })
+                .map(|fixture| fixture.name.clone());
+            let current_path = handle.path().as_path();
             // Module fixtures take precedence; discover conftests only after a local miss.
             let candidates = once(handle.clone())
                 .chain(once_with(|| pytest_conftest_handles(self, handle, preference)).flatten());
@@ -143,9 +153,16 @@ impl<'a> Transaction<'a> {
                 while seen.insert((target_handle.clone(), target_name.clone())) {
                     let exports = self.get_exports_data(&target_handle);
                     if let Some(fixture) = exports.pytest_fixtures().iter().find(|fixture| {
-                        if fixture.range == enclosing_function_range
-                            && target_handle.path().as_path() == handle.path().as_path()
-                        {
+                        let target_path = target_handle.path().as_path();
+                        let is_same_definition = fixture.range == enclosing_function_range
+                            && target_path == current_path;
+                        // The implementation and its stub denote the same module-level provider.
+                        let is_paired_definition = requesting_fixture_name.as_ref()
+                            == Some(&fixture.name)
+                            && target_handle.path().style() != handle.path().style()
+                            && target_path.parent() == current_path.parent()
+                            && target_path.file_stem() == current_path.file_stem();
+                        if is_same_definition || is_paired_definition {
                             return false;
                         }
                         if imported {

pyrefly/lib/test/lsp/definition.rs

@@ -1064,18 +1064,23 @@ fn pytest_conftest_override_requests_parent_with_companion_stub() {
             TextSize::try_from(code.find("local_answer(answer)").unwrap() + "local_answer(".len())
                 .unwrap();
         let transaction = state.transaction();
-        for definitions in [
-            transaction.goto_definition(&handle, position).unwrap(),
-            transaction.goto_declaration(&handle, position).unwrap(),
+        for (definitions, expected) in [
+            (
+                transaction.goto_definition(&handle, position).unwrap(),
+                "conftest.py",
+            ),
+            (
+                transaction.goto_declaration(&handle, position).unwrap(),
+                "conftest.pyi",
+            ),
         ] {
-            // BUG: the requesting fixture's companion is still selected instead of its parent.
             assert_eq!(
-                definitions[0].module.path().as_path().parent().unwrap(),
-                root.path().join("tests"),
+                definitions[0].module.path().as_path(),
+                root.path().join(expected),
             );
             assert_eq!(
                 definitions[0].module.code_at(definitions[0].range),
-                "local_answer",
+                "answer"
             );
         }
         let consumer_position = TextSize::try_from(test_code.find("answer").unwrap()).unwrap();