diff --git a/Lib/test/test_frame.py b/Lib/test/test_frame.py
new file mode 100644
index 000000000..ae02e2a59
--- /dev/null
+++ b/Lib/test/test_frame.py
@@ -0,0 +1,814 @@
+import copy
+import operator
+import re
+import sys
+import textwrap
+import threading
+import unittest
+import weakref
+try:
+    import _testcapi
+except ImportError:
+    _testcapi = None
+
+from collections.abc import Mapping
+from test import support
+from test.support import import_helper, threading_helper
+from test.support.script_helper import assert_python_ok
+from test import mapping_tests
+
+
+class ClearTest(unittest.TestCase):
+    """
+    Tests for frame.clear().
+    """
+
+    def inner(self, x=5, **kwargs):
+        1/0
+
+    def outer(self, **kwargs):
+        try:
+            self.inner(**kwargs)
+        except ZeroDivisionError as e:
+            exc = e
+        return exc
+
+    def clear_traceback_frames(self, tb):
+        """
+        Clear all frames in a traceback.
+        """
+        while tb is not None:
+            tb.tb_frame.clear()
+            tb = tb.tb_next
+
+    def test_clear_locals(self):
+        class C:
+            pass
+        c = C()
+        wr = weakref.ref(c)
+        exc = self.outer(c=c)
+        del c
+        support.gc_collect()
+        # A reference to c is held through the frames
+        self.assertIsNot(None, wr())
+        self.clear_traceback_frames(exc.__traceback__)
+        support.gc_collect()
+        # The reference was released by .clear()
+        self.assertIs(None, wr())
+
+    def test_clear_locals_after_f_locals_access(self):
+        # see gh-113939
+        class C:
+            pass
+
+        wr = None
+        def inner():
+            nonlocal wr
+            c = C()
+            wr = weakref.ref(c)
+            1/0
+
+        try:
+            inner()
+        except ZeroDivisionError as exc:
+            support.gc_collect()
+            self.assertIsNotNone(wr())
+            exc.__traceback__.tb_next.tb_frame.clear()
+            support.gc_collect()
+            self.assertIsNone(wr())
+
+    def test_clear_does_not_clear_specials(self):
+        class C:
+            pass
+        c = C()
+        exc = self.outer(c=c)
+        del c
+        f = exc.__traceback__.tb_frame
+        f.clear()
+        self.assertIsNot(f.f_code, None)
+        self.assertIsNot(f.f_locals, None)
+        self.assertIsNot(f.f_builtins, None)
+        self.assertIsNot(f.f_globals, None)
+
+    def test_clear_generator(self):
+        endly = False
+        def g():
+            nonlocal endly
+            try:
+                yield
+                self.inner()
+            finally:
+                endly = True
+        gen = g()
+        next(gen)
+        self.assertFalse(endly)
+
+        # Cannot clear a suspended frame
+        with self.assertRaisesRegex(RuntimeError, r'suspended frame'):
+            gen.gi_frame.clear()
+        self.assertFalse(endly)
+
+    def test_clear_executing(self):
+        # Attempting to clear an executing frame is forbidden.
+        try:
+            1/0
+        except ZeroDivisionError as e:
+            f = e.__traceback__.tb_frame
+        with self.assertRaises(RuntimeError):
+            f.clear()
+        with self.assertRaises(RuntimeError):
+            f.f_back.clear()
+
+    def test_clear_executing_generator(self):
+        # Attempting to clear an executing generator frame is forbidden.
+        endly = False
+        def g():
+            nonlocal endly
+            try:
+                1/0
+            except ZeroDivisionError as e:
+                f = e.__traceback__.tb_frame
+                with self.assertRaises(RuntimeError):
+                    f.clear()
+                with self.assertRaises(RuntimeError):
+                    f.f_back.clear()
+                yield f
+            finally:
+                endly = True
+        gen = g()
+        f = next(gen)
+        self.assertFalse(endly)
+        # Cannot clear a suspended frame
+        with self.assertRaisesRegex(RuntimeError, 'suspended frame'):
+            f.clear()
+        self.assertFalse(endly)
+
+    def test_lineno_with_tracing(self):
+        def record_line():
+            f = sys._getframe(1)
+            lines.append(f.f_lineno-f.f_code.co_firstlineno)
+
+        def test(trace):
+            record_line()
+            if trace:
+                sys._getframe(0).f_trace = True
+            record_line()
+            record_line()
+
+        expected_lines = [1, 4, 5]
+        lines = []
+        test(False)
+        self.assertEqual(lines, expected_lines)
+        lines = []
+        test(True)
+        self.assertEqual(lines, expected_lines)
+
+    @support.cpython_only
+    def test_clear_refcycles(self):
+        # .clear() doesn't leave any refcycle behind
+        with support.disable_gc():
+            class C:
+                pass
+            c = C()
+            wr = weakref.ref(c)
+            exc = self.outer(c=c)
+            del c
+            self.assertIsNot(None, wr())
+            self.clear_traceback_frames(exc.__traceback__)
+            self.assertIs(None, wr())
+
+
+class FrameAttrsTest(unittest.TestCase):
+
+    def make_frames(self):
+        def outer():
+            x = 5
+            y = 6
+            def inner():
+                z = x + 2
+                1/0
+                t = 9
+            return inner()
+        try:
+            outer()
+        except ZeroDivisionError as e:
+            tb = e.__traceback__
+            frames = []
+            while tb:
+                frames.append(tb.tb_frame)
+                tb = tb.tb_next
+        return frames
+
+    def test_clear_locals(self):
+        # Test f_locals after clear() (issue #21897)
+        f, outer, inner = self.make_frames()
+        outer.clear()
+        inner.clear()
+        self.assertEqual(outer.f_locals, {})
+        self.assertEqual(inner.f_locals, {})
+
+    def test_locals_clear_locals(self):
+        # Test f_locals before and after clear() (to exercise caching)
+        f, outer, inner = self.make_frames()
+        self.assertNotEqual(outer.f_locals, {})
+        self.assertNotEqual(inner.f_locals, {})
+        outer.clear()
+        inner.clear()
+        self.assertEqual(outer.f_locals, {})
+        self.assertEqual(inner.f_locals, {})
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; TypeError: can't delete f_lineno attribute
+    def test_f_lineno_del_segfault(self):
+        f, _, _ = self.make_frames()
+        with self.assertRaises(AttributeError):
+            del f.f_lineno
+
+    def test_f_generator(self):
+        # Test f_generator in different contexts.
+
+        def t0():
+            def nested():
+                frame = sys._getframe()
+                return frame.f_generator
+
+            def gen():
+                yield nested()
+
+            g = gen()
+            try:
+                return next(g)
+            finally:
+                g.close()
+
+        def t1():
+            frame = sys._getframe()
+            return frame.f_generator
+
+        def t2():
+            frame = sys._getframe()
+            yield frame.f_generator
+
+        async def t3():
+            frame = sys._getframe()
+            return frame.f_generator
+
+        # For regular functions f_generator is None
+        self.assertIsNone(t0())
+        self.assertIsNone(t1())
+
+        # For generators f_generator is equal to self
+        g = t2()
+        try:
+            frame_g = next(g)
+            self.assertIs(g, frame_g)
+        finally:
+            g.close()
+
+        # Ditto for coroutines
+        c = t3()
+        try:
+            c.send(None)
+        except StopIteration as ex:
+            self.assertIs(ex.value, c)
+        else:
+            raise AssertionError('coroutine did not exit')
+
+
+class ReprTest(unittest.TestCase):
+    """
+    Tests for repr(frame).
+    """
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON
+    def test_repr(self):
+        def outer():
+            x = 5
+            y = 6
+            def inner():
+                z = x + 2
+                1/0
+                t = 9
+            return inner()
+
+        offset = outer.__code__.co_firstlineno
+        try:
+            outer()
+        except ZeroDivisionError as e:
+            tb = e.__traceback__
+            frames = []
+            while tb:
+                frames.append(tb.tb_frame)
+                tb = tb.tb_next
+        else:
+            self.fail("should have raised")
+
+        f_this, f_outer, f_inner = frames
+        file_repr = re.escape(repr(__file__))
+        self.assertRegex(repr(f_this),
+                         r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code test_repr>$"
+                         % (file_repr, offset + 23))
+        self.assertRegex(repr(f_outer),
+                         r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code outer>$"
+                         % (file_repr, offset + 7))
+        self.assertRegex(repr(f_inner),
+                         r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code inner>$"
+                         % (file_repr, offset + 5))
+
+class TestFrameLocals(unittest.TestCase):
+    @unittest.expectedFailure  # TODO: RUSTPYTHON
+    def test_scope(self):
+        class A:
+            x = 1
+            sys._getframe().f_locals['x'] = 2
+            sys._getframe().f_locals['y'] = 2
+
+        self.assertEqual(A.x, 2)
+        self.assertEqual(A.y, 2)
+
+        def f():
+            x = 1
+            sys._getframe().f_locals['x'] = 2
+            sys._getframe().f_locals['y'] = 2
+            self.assertEqual(x, 2)
+            self.assertEqual(locals()['y'], 2)
+        f()
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: 1 != 2
+    def test_closure(self):
+        x = 1
+        y = 2
+
+        def f():
+            z = x + y
+            d = sys._getframe().f_locals
+            self.assertEqual(d['x'], 1)
+            self.assertEqual(d['y'], 2)
+            d['x'] = 2
+            d['y'] = 3
+
+        f()
+        self.assertEqual(x, 2)
+        self.assertEqual(y, 3)
+
+    def test_closure_with_inline_comprehension(self):
+        lambda: k
+        k = 1
+        lst = [locals() for k in [0]]
+        self.assertEqual(lst[0]['k'], 0)
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: 3 != 4
+    def test_as_dict(self):
+        x = 1
+        y = 2
+        d = sys._getframe().f_locals
+        # self, x, y, d
+        self.assertEqual(len(d), 4)
+        self.assertIs(d['d'], d)
+        self.assertEqual(set(d.keys()), set(['x', 'y', 'd', 'self']))
+        self.assertEqual(len(d.values()), 4)
+        self.assertIn(1, d.values())
+        self.assertEqual(len(d.items()), 4)
+        self.assertIn(('x', 1), d.items())
+        self.assertEqual(d.__getitem__('x'), 1)
+        d.__setitem__('x', 2)
+        self.assertEqual(d['x'], 2)
+        self.assertEqual(d.get('x'), 2)
+        self.assertIs(d.get('non_exist', None), None)
+        self.assertEqual(d.__len__(), 4)
+        self.assertEqual(set([key for key in d]), set(['x', 'y', 'd', 'self']))
+        self.assertIn('x', d)
+        self.assertTrue(d.__contains__('x'))
+
+        self.assertEqual(reversed(d), list(reversed(d.keys())))
+
+        d.update({'x': 3, 'z': 4})
+        self.assertEqual(d['x'], 3)
+        self.assertEqual(d['z'], 4)
+
+        with self.assertRaises(TypeError):
+            d.update([1, 2])
+
+        self.assertEqual(d.setdefault('x', 5), 3)
+        self.assertEqual(d.setdefault('new', 5), 5)
+        self.assertEqual(d['new'], 5)
+
+        with self.assertRaises(KeyError):
+            d['non_exist']
+
+    def test_as_number(self):
+        x = 1
+        y = 2
+        d = sys._getframe().f_locals
+        self.assertIn('z', d | {'z': 3})
+        d |= {'z': 3}
+        self.assertEqual(d['z'], 3)
+        d |= {'y': 3}
+        self.assertEqual(d['y'], 3)
+        with self.assertRaises(TypeError):
+            d |= 3
+        with self.assertRaises(TypeError):
+            _ = d | [3]
+
+    def test_non_string_key(self):
+        d = sys._getframe().f_locals
+        d[1] = 2
+        self.assertEqual(d[1], 2)
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; UnboundLocalError: local variable 'b' referenced before assignment
+    def test_write_with_hidden(self):
+        def f():
+            f_locals = [sys._getframe().f_locals for b in [0]][0]
+            f_locals['b'] = 2
+            f_locals['c'] = 3
+            self.assertEqual(b, 2)
+            self.assertEqual(c, 3)
+            b = 0
+            c = 0
+        f()
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: <object object at 0xb4000072b6930480> != 'a.b.c'
+    def test_local_objects(self):
+        o = object()
+        k = '.'.join(['a', 'b', 'c'])
+        f_locals = sys._getframe().f_locals
+        f_locals['o'] = f_locals['k']
+        self.assertEqual(o, 'a.b.c')
+
+    def test_copy(self):
+        x = 0
+        d = sys._getframe().f_locals
+        d_copy = d.copy()
+        self.assertIsInstance(d_copy, dict)
+        self.assertEqual(d_copy['x'], 0)
+        d_copy['x'] = 1
+        self.assertEqual(x, 0)
+
+    def test_update_with_self(self):
+        def f():
+            f_locals = sys._getframe().f_locals
+            f_locals.update(f_locals)
+            f_locals.update(f_locals)
+            f_locals.update(f_locals)
+        f()
+
+    def test_repr(self):
+        x = 1
+        # Introduce a reference cycle
+        frame = sys._getframe()
+        self.assertEqual(repr(frame.f_locals), repr(dict(frame.f_locals)))
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: ValueError not raised
+    def test_delete(self):
+        x = 1
+        d = sys._getframe().f_locals
+
+        # This needs to be tested before f_extra_locals is created
+        with self.assertRaisesRegex(KeyError, 'non_exist'):
+            del d['non_exist']
+
+        with self.assertRaises(KeyError):
+            d.pop('non_exist')
+
+        with self.assertRaisesRegex(ValueError, 'local variables'):
+            del d['x']
+
+        with self.assertRaises(AttributeError):
+            d.clear()
+
+        with self.assertRaises(ValueError):
+            d.pop('x')
+
+        with self.assertRaises(ValueError):
+            d.pop('x', None)
+
+        # 'm', 'n' is stored in f_extra_locals
+        d['m'] = 1
+        d['n'] = 1
+
+        with self.assertRaises(KeyError):
+            d.pop('non_exist')
+
+        del d['m']
+        self.assertEqual(d.pop('n'), 1)
+
+        self.assertNotIn('m', d)
+        self.assertNotIn('n', d)
+
+        self.assertEqual(d.pop('n', 2), 2)
+
+    @support.cpython_only
+    def test_sizeof(self):
+        proxy = sys._getframe().f_locals
+        support.check_sizeof(self, proxy, support.calcobjsize("P"))
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: TypeError not raised
+    def test_unsupport(self):
+        x = 1
+        d = sys._getframe().f_locals
+        with self.assertRaises(TypeError):
+            copy.copy(d)
+
+        with self.assertRaises(TypeError):
+            copy.deepcopy(d)
+
+    def test_is_mapping(self):
+        x = 1
+        d = sys._getframe().f_locals
+        self.assertIsInstance(d, Mapping)
+        match d:
+            case {"x": value}:
+                self.assertEqual(value, 1)
+                kind = "mapping"
+            case _:
+                kind = "other"
+        self.assertEqual(kind, "mapping")
+
+    def _x_stringlikes(self):
+        class StringSubclass(str):
+            pass
+
+        class ImpostorX:
+            def __hash__(self):
+                return hash('x')
+
+            def __eq__(self, other):
+                return other == 'x'
+
+        return StringSubclass('x'), ImpostorX(), 'x'
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: dict_keys(['obj', 'x']) != ['obj', 'x', 'proxy']
+    def test_proxy_key_stringlikes_overwrite(self):
+        def f(obj):
+            x = 1
+            proxy = sys._getframe().f_locals
+            proxy[obj] = 2
+            return (
+                list(proxy.keys()),
+                dict(proxy),
+                proxy
+            )
+
+        for obj in self._x_stringlikes():
+            with self.subTest(cls=type(obj).__name__):
+
+                keys_snapshot, proxy_snapshot, proxy = f(obj)
+                expected_keys = ['obj', 'x', 'proxy']
+                expected_dict = {'obj': 'x', 'x': 2, 'proxy': proxy}
+                self.assertEqual(proxy.keys(),  expected_keys)
+                self.assertEqual(proxy, expected_dict)
+                self.assertEqual(keys_snapshot,  expected_keys)
+                self.assertEqual(proxy_snapshot, expected_dict)
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; UnboundLocalError: local variable 'b' referenced before assignment
+    def test_proxy_key_stringlikes_ftrst_write(self):
+        def f(obj):
+            proxy = sys._getframe().f_locals
+            proxy[obj] = 2
+            self.assertEqual(x, 2)
+            x = 1
+
+        for obj in self._x_stringlikes():
+            with self.subTest(cls=type(obj).__name__):
+                f(obj)
+
+    def test_proxy_key_unhashables(self):
+        class StringSubclass(str):
+            __hash__ = None
+
+        class ObjectSubclass:
+            __hash__ = None
+
+        proxy = sys._getframe().f_locals
+
+        for obj in StringSubclass('x'), ObjectSubclass():
+            with self.subTest(cls=type(obj).__name__):
+                with self.assertRaises(TypeError):
+                    proxy[obj]
+                with self.assertRaises(TypeError):
+                    proxy[obj] = 0
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: 'dict' != 'FrameLocalsProxy'
+    def test_constructor(self):
+        FrameLocalsProxy = type([sys._getframe().f_locals
+                                 for x in range(1)][0])
+        self.assertEqual(FrameLocalsProxy.__name__, 'FrameLocalsProxy')
+
+        def make_frame():
+            x = 1
+            y = 2
+            return sys._getframe()
+
+        proxy = FrameLocalsProxy(make_frame())
+        self.assertEqual(proxy, {'x': 1, 'y': 2})
+
+        # constructor expects 1 frame argument
+        with self.assertRaises(TypeError):
+            FrameLocalsProxy()     # no arguments
+        with self.assertRaises(TypeError):
+            FrameLocalsProxy(123)  # wrong type
+        with self.assertRaises(TypeError):
+            FrameLocalsProxy(frame=sys._getframe())  # no keyword arguments
+
+    def test_overwrite_locals(self):
+        # Verify we do not crash if we overwrite a local passed as an argument
+        # from an ancestor in the call stack.
+        def f():
+            xs = [1, 2, 3]
+            ys = [4, 5, 6]
+            return g(xs)
+
+        def g(xs):
+            f = sys._getframe()
+            f.f_back.f_locals["xs"] = None
+            f.f_back.f_locals["ys"] = None
+            return xs[1]
+
+        self.assertEqual(f(), 2)
+
+
+class FrameLocalsProxyMappingTests(mapping_tests.TestHashMappingProtocol):
+    """Test that FrameLocalsProxy behaves like a Mapping (with exceptions)"""
+
+    def _f(*args, **kwargs):
+        def _f():
+            return sys._getframe().f_locals
+        return _f()
+    type2test = _f
+
+    @unittest.skipIf(True, 'Locals proxies for different frames never compare as equal')
+    def test_constructor(self):
+        pass
+
+    @unittest.skipIf(True, 'Unlike a mapping: del proxy[key] fails')
+    def test_write(self):
+        pass
+
+    @unittest.skipIf(True, 'Unlike a mapping: no proxy.popitem')
+    def test_popitem(self):
+        pass
+
+    @unittest.skipIf(True, 'Unlike a mapping: no proxy.pop')
+    def test_pop(self):
+        pass
+
+    @unittest.skipIf(True, 'Unlike a mapping: no proxy.clear')
+    def test_clear(self):
+        pass
+
+    @unittest.skipIf(True, 'Unlike a mapping: no proxy.fromkeys')
+    def test_fromkeys(self):
+        pass
+
+    # no del
+    def test_getitem(self):
+        mapping_tests.BasicTestMappingProtocol.test_getitem(self)
+        d = self._full_mapping({'a': 1, 'b': 2})
+        self.assertEqual(d['a'], 1)
+        self.assertEqual(d['b'], 2)
+        d['c'] = 3
+        d['a'] = 4
+        self.assertEqual(d['c'], 3)
+        self.assertEqual(d['a'], 4)
+
+    @unittest.skipIf(True, 'Unlike a mapping: no proxy.update')
+    def test_update(self):
+        pass
+
+    # proxy.copy returns a regular dict
+    def test_copy(self):
+        d = self._full_mapping({1:1, 2:2, 3:3})
+        self.assertEqual(d.copy(), {1:1, 2:2, 3:3})
+        d = self._empty_mapping()
+        self.assertEqual(d.copy(), d)
+        self.assertRaises(TypeError, d.copy, None)
+
+        self.assertIsInstance(d.copy(), dict)
+
+    @unittest.skipIf(True, 'Locals proxies for different frames never compare as equal')
+    def test_eq(self):
+        pass
+
+
+class TestFrameCApi(unittest.TestCase):
+    @unittest.expectedFailure  # TODO: RUSTPYTHON
+    def test_basic(self):
+        x = 1
+        ctypes = import_helper.import_module('ctypes')
+        PyEval_GetFrameLocals = ctypes.pythonapi.PyEval_GetFrameLocals
+        PyEval_GetFrameLocals.restype = ctypes.py_object
+        frame_locals = PyEval_GetFrameLocals()
+        self.assertTrue(type(frame_locals), dict)
+        self.assertEqual(frame_locals['x'], 1)
+        frame_locals['x'] = 2
+        self.assertEqual(x, 1)
+
+        PyEval_GetFrameGlobals = ctypes.pythonapi.PyEval_GetFrameGlobals
+        PyEval_GetFrameGlobals.restype = ctypes.py_object
+        frame_globals = PyEval_GetFrameGlobals()
+        self.assertTrue(type(frame_globals), dict)
+        self.assertIs(frame_globals, globals())
+
+        PyEval_GetFrameBuiltins = ctypes.pythonapi.PyEval_GetFrameBuiltins
+        PyEval_GetFrameBuiltins.restype = ctypes.py_object
+        frame_builtins = PyEval_GetFrameBuiltins()
+        self.assertEqual(frame_builtins, __builtins__)
+
+        PyFrame_GetLocals = ctypes.pythonapi.PyFrame_GetLocals
+        PyFrame_GetLocals.argtypes = [ctypes.py_object]
+        PyFrame_GetLocals.restype = ctypes.py_object
+        frame = sys._getframe()
+        f_locals = PyFrame_GetLocals(frame)
+        self.assertTrue(f_locals['x'], 1)
+        f_locals['x'] = 2
+        self.assertEqual(x, 2)
+
+
+class TestIncompleteFrameAreInvisible(unittest.TestCase):
+
+    def test_issue95818(self):
+        # See GH-95818 for details
+        code = textwrap.dedent(f"""
+            import gc
+
+            gc.set_threshold(1,1,1)
+            class GCHello:
+                def __del__(self):
+                    print("Destroyed from gc")
+
+            def gen():
+                yield
+
+            fd = open({__file__!r})
+            l = [fd, GCHello()]
+            l.append(l)
+            del fd
+            del l
+            gen()
+        """)
+        assert_python_ok("-c", code)
+
+    @support.cpython_only
+    @threading_helper.requires_working_threading()
+    def test_sneaky_frame_object_teardown(self):
+
+        class SneakyDel:
+            def __del__(self):
+                """
+                Stash a reference to the entire stack for walking later.
+
+                It may look crazy, but you'd be surprised how common this is
+                when using a test runner (like pytest). The typical recipe is:
+                ResourceWarning + -Werror + a custom sys.unraisablehook.
+                """
+                nonlocal sneaky_frame_object
+                sneaky_frame_object = sys._getframe()
+
+        class SneakyThread(threading.Thread):
+            """
+            A separate thread isn't needed to make this code crash, but it does
+            make crashes more consistent, since it means sneaky_frame_object is
+            backed by freed memory after the thread completes!
+            """
+
+            def run(self):
+                """Run SneakyDel.__del__ as this frame is popped."""
+                ref = SneakyDel()
+
+        sneaky_frame_object = None
+        t = SneakyThread()
+        t.start()
+        t.join()
+        # sneaky_frame_object can be anything, really, but it's crucial that
+        # SneakyThread.run's frame isn't anywhere on the stack while it's being
+        # torn down:
+        self.assertIsNotNone(sneaky_frame_object)
+        while sneaky_frame_object is not None:
+            self.assertIsNot(
+                sneaky_frame_object.f_code, SneakyThread.run.__code__
+            )
+            sneaky_frame_object = sneaky_frame_object.f_back
+
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; AttributeError: 'NoneType' object has no attribute 'exc_type'
+    def test_entry_frames_are_invisible_during_teardown(self):
+        class C:
+            """A weakref'able 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())
+
+
+if __name__ == "__main__":
+    unittest.main()