1 files changed, 8 insertions, 0 deletions
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index 47dc0b9..a2a5d8f 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -1422,6 +1422,14 @@ class ProtocolTests(BaseTestCase):
         class CustomContextManager(typing.ContextManager, Protocol):
             pass
 
+    def test_non_runtime_protocol_isinstance_check(self):
+        class P(Protocol):
+            x: int
+
+        with self.assertRaisesRegex(TypeError, "@runtime_checkable"):
+            isinstance(1, P)
+
+
 class GenericTests(BaseTestCase):
 
     def test_basics(self):