1 files changed, 16 insertions, 0 deletions
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index b4a5a68..098933b 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -3546,6 +3546,22 @@ class ProtocolTests(BaseTestCase):
         self.assertIsSubclass(B, Custom)
         self.assertNotIsSubclass(A, Custom)
 
+        @runtime_checkable
+        class ReleasableBuffer(collections.abc.Buffer, Protocol):
+            def __release_buffer__(self, mv: memoryview) -> None: ...
+
+        class C: pass
+        class D:
+            def __buffer__(self, flags: int) -> memoryview:
+                return memoryview(b'')
+            def __release_buffer__(self, mv: memoryview) -> None:
+                pass
+
+        self.assertIsSubclass(D, ReleasableBuffer)
+        self.assertIsInstance(D(), ReleasableBuffer)
+        self.assertNotIsSubclass(C, ReleasableBuffer)
+        self.assertNotIsInstance(C(), ReleasableBuffer)
+
     def test_builtin_protocol_allowlist(self):
         with self.assertRaises(TypeError):
             class CustomProtocol(TestCase, Protocol):