bpo-32226: Make __class_getitem__ an automatic class method. (#5098)

1 files changed, 11 insertions, 2 deletions

diff --git a/Lib/test/test_genericclass.py b/Lib/test/test_genericclass.py
index 2057fc0..37e755b 100644
--- a/Lib/test/test_genericclass.py
+++ b/Lib/test/test_genericclass.py
@@ -183,12 +183,21 @@ class TestClassGetitem(unittest.TestCase):
         self.assertEqual(D[int], 'D[int]')
         self.assertEqual(D[D], 'D[D]')
 
+    def test_class_getitem_classmethod(self):
+        class C:
+            @classmethod
+            def __class_getitem__(cls, item):
+                return f'{cls.__name__}[{item.__name__}]'
+        class D(C): ...
+        self.assertEqual(D[int], 'D[int]')
+        self.assertEqual(D[D], 'D[D]')
+
     def test_class_getitem_patched(self):
         class C:
             def __init_subclass__(cls):
                 def __class_getitem__(cls, item):
                     return f'{cls.__name__}[{item.__name__}]'
-                cls.__class_getitem__ = __class_getitem__
+                cls.__class_getitem__ = classmethod(__class_getitem__)
         class D(C): ...
         self.assertEqual(D[int], 'D[int]')
         self.assertEqual(D[D], 'D[D]')
@@ -254,7 +263,7 @@ class CAPITest(unittest.TestCase):
 
     def test_c_class(self):
         from _testcapi import Generic, GenericAlias
-        self.assertIsInstance(Generic.__class_getitem__(Generic, int), GenericAlias)
+        self.assertIsInstance(Generic.__class_getitem__(int), GenericAlias)
 
         IntGeneric = Generic[int]
         self.assertIs(type(IntGeneric), GenericAlias)