fix: replace co_filename with the correct filename when the file is moved

Author: 15r10nk

changelog/14552.bugfix.rst

@@ -0,0 +1,2 @@
+Fixed assertion-rewrite cache behavior for moved test files: when a rewritten ``.pyc`` was reused after renaming or moving a test module/directory, nested code objects could keep a stale ``co_filename`` from the old path. This caused ``inspect.currentframe().f_code.co_filename`` (and related traceback/reporting paths) to point to the previous location instead of the current file path.
+

src/_pytest/assertion/rewrite.py

@@ -397,9 +397,28 @@ def _read_pyc(
         if not isinstance(co, types.CodeType):
             trace(f"_read_pyc({source}): not a code object")
             return None
+        # A cached pyc can be moved together with the source file (for example
+        # by renaming a package or test directory). In that case, the marshaled
+        # code object's ``co_filename`` still points to the old source path,
+        # which leaks stale filenames in tracebacks and ``inspect``.
+        source_str = str(source)
+        if co.co_filename != source_str:
+            co = _replace_code_filenames(co, source_str)
         return co
 
 
+def _replace_code_filenames(co: types.CodeType, filename: str) -> types.CodeType:
+    return co.replace(
+        co_filename=filename,
+        co_consts=tuple(
+            _replace_code_filenames(const, filename)
+            if isinstance(const, types.CodeType)
+            else const
+            for const in co.co_consts
+        ),
+    )
+
+
 def rewrite_asserts(
     mod: ast.Module,
     source: bytes,

testing/test_assertrewrite.py

@@ -1138,6 +1138,31 @@ def test_foo():
             glob.glob("__pycache__/*.pyc")
         )
 
+    def test_moved_test_file_updates_code_filename(
+        self, pytester: Pytester, monkeypatch: pytest.MonkeyPatch
+    ) -> None:
+        """Moving a test module must keep ``co_filename`` synchronized with ``__file__``."""
+        monkeypatch.delenv("PYTHONPYCACHEPREFIX", raising=False)
+
+        pytester.makepyfile(
+            **{
+                "test1/test_a.py": """
+                from inspect import currentframe
+
+                def test_a():
+                    assert currentframe().f_code.co_filename == __file__
+                """
+            }
+        )
+
+        first = pytester.runpytest_subprocess("-s", "test1/test_a.py")
+        first.assert_outcomes(passed=1)
+
+        pytester.path.joinpath("test1").rename(pytester.path.joinpath("test2"))
+
+        second = pytester.runpytest_subprocess("-s", "test2/test_a.py")
+        second.assert_outcomes(passed=1)
+
     @pytest.mark.skipif('"__pypy__" in sys.modules')
     def test_pyc_vs_pyo(
         self,