bpo-32467: Let collections.abc.ValuesView inherit from Collection (#5152)

Doc/library/collections.abc.rst

@@ -87,7 +87,8 @@ ABC                        Inherits from          Abstract Methods        Mixin
                            :class:`Set`                                   ``__iter__``
 :class:`KeysView`          :class:`MappingView`,                          ``__contains__``,
                            :class:`Set`                                   ``__iter__``
-:class:`ValuesView`        :class:`MappingView`                           ``__contains__``, ``__iter__``
+:class:`ValuesView`        :class:`MappingView`,                          ``__contains__``, ``__iter__``
+                           :class:`Collection`
 :class:`Awaitable`                                ``__await__``
 :class:`Coroutine`         :class:`Awaitable`     ``send``, ``throw``     ``close``
 :class:`AsyncIterable`                            ``__aiter__``

Lib/_collections_abc.py

@@ -746,7 +746,7 @@ class ItemsView(MappingView, Set):
 ItemsView.register(dict_items)
 
 
-class ValuesView(MappingView):
+class ValuesView(MappingView, Collection):
 
     __slots__ = ()
 

Lib/test/test_collections.py

@@ -843,13 +843,13 @@ class TestOneTrickPonyABCs(ABCTestCase):
             self.assertFalse(issubclass(type(x), Collection), repr(type(x)))
         # Check some non-collection iterables
         non_col_iterables = [_test_gen(), iter(b''), iter(bytearray()),
-                             (x for x in []), dict().values()]
+                             (x for x in [])]
         for x in non_col_iterables:
             self.assertNotIsInstance(x, Collection)
             self.assertFalse(issubclass(type(x), Collection), repr(type(x)))
         # Check some collections
         samples = [set(), frozenset(), dict(), bytes(), str(), tuple(),
-                   list(), dict().keys(), dict().items()]
+                   list(), dict().keys(), dict().items(), dict().values()]
         for x in samples:
             self.assertIsInstance(x, Collection)
             self.assertTrue(issubclass(type(x), Collection), repr(type(x)))

Misc/NEWS.d/next/Library/2018-01-11-00-33-42.bpo-32467.YVEOv6.rst

+collections.abc.ValuesView now inherits from collections.abc.Collection.