bpo-46345: Add a test case for implicit Optional class attribute (GH-30535)

(cherry picked from commit 1de6015)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>

Author: miss-islington

Lib/test/test_typing.py

@@ -3104,6 +3104,12 @@ def test_get_type_hints_classes(self):
                           'my_inner_a2': mod_generics_cache.B.A,
                           'my_outer_a': mod_generics_cache.A})
 
+    def test_get_type_hints_classes_no_implicit_optional(self):
+        class WithNoneDefault:
+            field: int = None  # most type-checkers won't be happy with it
+
+        self.assertEqual(gth(WithNoneDefault), {'field': int})
+
     def test_respect_no_type_check(self):
         @no_type_check
         class NoTpCheck: