[3.9] bpo-42332: Add weakref slot to types.GenericAlias (GH-23250) (GH-23309)



(cherry picked from commit 384b7a4bd988986bca227c7e85c32d766da74708)
diff --git a/Lib/test/test_genericalias.py b/Lib/test/test_genericalias.py
index 240aad0..912fb33 100644
--- a/Lib/test/test_genericalias.py
+++ b/Lib/test/test_genericalias.py
@@ -13,7 +13,10 @@
 from dataclasses import Field
 from functools import partial, partialmethod, cached_property
 from mailbox import Mailbox, _PartialFile
-from ctypes import Array, LibraryLoader
+try:
+    import ctypes
+except ImportError:
+    ctypes = None
 from difflib import SequenceMatcher
 from filecmp import dircmp
 from fileinput import FileInput
@@ -44,45 +47,46 @@
 
 class BaseTest(unittest.TestCase):
     """Test basics."""
+    generic_types = [type, tuple, list, dict, set, frozenset, enumerate,
+                     defaultdict, deque,
+                     SequenceMatcher,
+                     dircmp,
+                     FileInput,
+                     OrderedDict, Counter, UserDict, UserList,
+                     Pattern, Match,
+                     partial, partialmethod, cached_property,
+                     AbstractContextManager, AbstractAsyncContextManager,
+                     Awaitable, Coroutine,
+                     AsyncIterable, AsyncIterator,
+                     AsyncGenerator, Generator,
+                     Iterable, Iterator,
+                     Reversible,
+                     Container, Collection,
+                     Callable,
+                     Mailbox, _PartialFile,
+                     ContextVar, Token,
+                     Field,
+                     Set, MutableSet,
+                     Mapping, MutableMapping, MappingView,
+                     KeysView, ItemsView, ValuesView,
+                     Sequence, MutableSequence,
+                     MappingProxyType, AsyncGeneratorType,
+                     DirEntry,
+                     chain,
+                     TemporaryDirectory, SpooledTemporaryFile,
+                     Queue, SimpleQueue,
+                     _AssertRaisesContext,
+                     SplitResult, ParseResult,
+                     ValueProxy, ApplyResult,
+                     WeakSet, ReferenceType, ref,
+                     ShareableList, MPSimpleQueue,
+                     Future, _WorkItem,
+                     Morsel]
+    if ctypes is not None:
+        generic_types.extend((ctypes.Array, ctypes.LibraryLoader))
 
     def test_subscriptable(self):
-        for t in (type, tuple, list, dict, set, frozenset, enumerate,
-                  defaultdict, deque,
-                  SequenceMatcher,
-                  dircmp,
-                  FileInput,
-                  OrderedDict, Counter, UserDict, UserList,
-                  Pattern, Match,
-                  partial, partialmethod, cached_property,
-                  AbstractContextManager, AbstractAsyncContextManager,
-                  Awaitable, Coroutine,
-                  AsyncIterable, AsyncIterator,
-                  AsyncGenerator, Generator,
-                  Iterable, Iterator,
-                  Reversible,
-                  Container, Collection,
-                  Callable,
-                  Mailbox, _PartialFile,
-                  ContextVar, Token,
-                  Field,
-                  Set, MutableSet,
-                  Mapping, MutableMapping, MappingView,
-                  KeysView, ItemsView, ValuesView,
-                  Sequence, MutableSequence,
-                  MappingProxyType, AsyncGeneratorType,
-                  DirEntry,
-                  chain,
-                  TemporaryDirectory, SpooledTemporaryFile,
-                  Queue, SimpleQueue,
-                  _AssertRaisesContext,
-                  Array, LibraryLoader,
-                  SplitResult, ParseResult,
-                  ValueProxy, ApplyResult,
-                  WeakSet, ReferenceType, ref,
-                  ShareableList, MPSimpleQueue,
-                  Future, _WorkItem,
-                  Morsel,
-                  ):
+        for t in self.generic_types:
             if t is None:
                 continue
             tname = t.__name__
@@ -289,5 +293,15 @@
         for generic_alias_property in ("__origin__", "__args__", "__parameters__"):
             self.assertIn(generic_alias_property, dir_of_gen_alias)
 
+    def test_weakref(self):
+        for t in self.generic_types:
+            if t is None:
+                continue
+            tname = t.__name__
+            with self.subTest(f"Testing {tname}"):
+                alias = t[int]
+                self.assertEqual(ref(alias)(), alias)
+
+
 if __name__ == "__main__":
     unittest.main()