1 files changed, 8 insertions, 0 deletions
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index ba0800f..3402996 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -1381,6 +1381,14 @@ class ProtocolTests(BaseTestCase):
         self.assertIsSubclass(B, Custom)
         self.assertNotIsSubclass(A, Custom)
 
+    def test_builtin_protocol_whitelist(self):
+        with self.assertRaises(TypeError):
+            class CustomProtocol(TestCase, Protocol):
+                pass
+
+        class CustomContextManager(typing.ContextManager, Protocol):
+            pass
+
 class GenericTests(BaseTestCase):
 
     def test_basics(self):