gh-133211: Test that PEP750 types are final (#133212)

diff --git a/Lib/test/test_string/test_templatelib.py b/Lib/test/test_string/test_templatelib.py
index 5cf187828510c4c6cab5ad8707580d9bd9248035..5221ca673b24ec6ca5f16eac42aa1cdde2e70599 100644 (file)
--- a/Lib/test/test_string/test_templatelib.py
+++ b/Lib/test/test_string/test_templatelib.py
@@ -18,6 +18,13 @@ class TestTemplate(unittest.TestCase, TStringBaseCase):
         self.assertEqual(type(i).__qualname__, 'Interpolation')
         self.assertEqual(type(i).__module__, 'string.templatelib')
 
+    def test_final_types(self):
+        with self.assertRaisesRegex(TypeError, 'is not an acceptable base type'):
+            class Sub(Template): ...
+
+        with self.assertRaisesRegex(TypeError, 'is not an acceptable base type'):
+            class Sub(Interpolation): ...
+
     def test_basic_creation(self):
         # Simple t-string creation
         t = t'Hello, world'