bpo-32999: Fix ABC.__subclasscheck__ crash (GH-6002)

1 files changed, 18 insertions, 0 deletions

diff --git a/Lib/test/test_abc.py b/Lib/test/test_abc.py
index af26c1d..6fc3c95 100644
--- a/Lib/test/test_abc.py
+++ b/Lib/test/test_abc.py
@@ -392,6 +392,24 @@ def test_factory(abc_ABCMeta, abc_get_cache_token):
             self.assertIsInstance(42, A)
             self.assertIsInstance(42, (A,))
 
+        def test_issubclass_bad_arguments(self):
+            class A(metaclass=abc_ABCMeta):
+                pass
+
+            with self.assertRaises(TypeError):
+                issubclass({}, A)  # unhashable
+
+            with self.assertRaises(TypeError):
+                issubclass(42, A)  # No __mro__
+
+            # Python version supports any iterable as __mro__.
+            # But it's implementation detail and don't emulate it in C version.
+            class C:
+                __mro__ = 42  # __mro__ is not tuple
+
+            with self.assertRaises(TypeError):
+                issubclass(C(), A)
+
         def test_all_new_methods_are_called(self):
             class A(metaclass=abc_ABCMeta):
                 pass