[3.6] bpo-28556: Update to typing: treat subscripted generics as proxies (GH-265) (GH-268)

(cherry picked from commit abb3b8ad94d699c8560d94ee9bac9c917b382abe)
(cherry picked from commit 365cb5bb9069273e6970c9d5d17ee2fe5003e7ac)

1 files changed, 35 insertions, 0 deletions

diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index 64d8276..f0070ec 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -674,6 +674,41 @@ class GenericTests(BaseTestCase):
         c.bar = 'abc'
         self.assertEqual(c.__dict__, {'bar': 'abc'})
 
+    def test_subscripted_generics_as_proxies(self):
+        T = TypeVar('T')
+        class C(Generic[T]):
+            x = 'def'
+        self.assertEqual(C[int].x, 'def')
+        self.assertEqual(C[C[int]].x, 'def')
+        C[C[int]].x = 'changed'
+        self.assertEqual(C.x, 'changed')
+        self.assertEqual(C[str].x, 'changed')
+        C[List[str]].z = 'new'
+        self.assertEqual(C.z, 'new')
+        self.assertEqual(C[Tuple[int]].z, 'new')
+
+        self.assertEqual(C().x, 'changed')
+        self.assertEqual(C[Tuple[str]]().z, 'new')
+
+        class D(C[T]):
+            pass
+        self.assertEqual(D[int].x, 'changed')
+        self.assertEqual(D.z, 'new')
+        D.z = 'from derived z'
+        D[int].x = 'from derived x'
+        self.assertEqual(C.x, 'changed')
+        self.assertEqual(C[int].z, 'new')
+        self.assertEqual(D.x, 'from derived x')
+        self.assertEqual(D[str].z, 'from derived z')
+
+    def test_abc_registry_kept(self):
+        T = TypeVar('T')
+        class C(Generic[T]): ...
+        C.register(int)
+        self.assertIsInstance(1, C)
+        C[int]
+        self.assertIsInstance(1, C)
+
     def test_false_subclasses(self):
         class MyMapping(MutableMapping[str, str]): pass
         self.assertNotIsInstance({}, MyMapping)