Add a failing regression test

brandtbucher · brandtbucher · commit 5f182009d153 · 2022-12-29T04:40:29.000-08:00
diff --git a/Lib/test/test_frame.py b/Lib/test/test_frame.py
@@ -1,4 +1,5 @@
 import gc
+import operator
 import re
 import sys
 import textwrap
@@ -372,6 +373,26 @@ def run(self):
             )
             sneaky_frame_object = sneaky_frame_object.f_back
 
+    def test_entry_frames_are_invisible_during_teardown(self):
+        class C:
+            """A weakrefable class."""
+
+        def f():
+            """Try to find globals and locals as this frame is being cleared."""
+            ref = C()
+            # Ignore the fact that exec(C()) is a nonsense callback. We're only
+            # using exec here because it tries to access the current frame's
+            # globals and locals. If it's trying to get those from a shim frame,
+            # we'll crash before raising:
+            return weakref.ref(ref, exec)
+
+        with support.catch_unraisable_exception() as catcher:
+            # Call from C, so there is a shim frame directly above f:
+            weak = operator.call(f)  # BOOM!
+            # Cool, we didn't crash. Check that the callback actually happened:
+            self.assertIs(catcher.unraisable.exc_type, TypeError)
+        self.assertIsNone(weak())
+
 @unittest.skipIf(_testcapi is None, 'need _testcapi')
 class TestCAPI(unittest.TestCase):
     def getframe(self):
