From bad9296fb0424bc480fa0ecfd2d60f73c33358f5 Mon Sep 17 00:00:00 2001
From: sobolevn <mail@sobolevn.me>
Date: Tue, 5 May 2026 17:58:49 +0300
Subject: [PATCH] gh-149410: Test that `typing.NoDefault` is final (#149411)

---
 Lib/test/test_typing.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index 5d19e370680..ad644bb3128 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -11131,6 +11131,10 @@ def test_no_attributes(self):
         with self.assertRaises(AttributeError):
             type(NoDefault).foo
 
+    def test_no_subclassing(self):
+        with self.assertRaises(TypeError):
+            class Test(type(NoDefault)): ...
+
 
 class AllTests(BaseTestCase):
     """Tests for __all__."""