Add collections.Reversible. Patch by Ivan Levkivskyi. Fixes issue #25987.
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 4c32e09..4202462 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -20,7 +20,7 @@
from collections import ChainMap
from collections import deque
from collections.abc import Awaitable, Coroutine, AsyncIterator, AsyncIterable
-from collections.abc import Hashable, Iterable, Iterator, Generator
+from collections.abc import Hashable, Iterable, Iterator, Generator, Reversible
from collections.abc import Sized, Container, Callable
from collections.abc import Set, MutableSet
from collections.abc import Mapping, MutableMapping, KeysView, ItemsView
@@ -689,6 +689,31 @@
self.validate_abstract_methods(Iterable, '__iter__')
self.validate_isinstance(Iterable, '__iter__')
+ def test_Reversible(self):
+ # Check some non-reversibles
+ non_samples = [None, 42, 3.14, 1j, dict(), set(), frozenset()]
+ for x in non_samples:
+ self.assertNotIsInstance(x, Reversible)
+ self.assertFalse(issubclass(type(x), Reversible), repr(type(x)))
+ # Check some reversibles
+ samples = [tuple(), list()]
+ for x in samples:
+ self.assertIsInstance(x, Reversible)
+ self.assertTrue(issubclass(type(x), Reversible), repr(type(x)))
+ # Check also Mapping, MutableMapping, and Sequence
+ self.assertTrue(issubclass(Sequence, Reversible), repr(Sequence))
+ self.assertFalse(issubclass(Mapping, Reversible), repr(Mapping))
+ self.assertFalse(issubclass(MutableMapping, Reversible), repr(MutableMapping))
+ # Check direct subclassing
+ class R(Reversible):
+ def __iter__(self):
+ return iter(list())
+ def __reversed__(self):
+ return iter(list())
+ self.assertEqual(list(reversed(R())), [])
+ self.assertFalse(issubclass(float, R))
+ self.validate_abstract_methods(Reversible, '__reversed__', '__iter__')
+
def test_Iterator(self):
non_samples = [None, 42, 3.14, 1j, b"", "", (), [], {}, set()]
for x in non_samples:
@@ -842,14 +867,14 @@
self.validate_isinstance(Callable, '__call__')
def test_direct_subclassing(self):
- for B in Hashable, Iterable, Iterator, Sized, Container, Callable:
+ for B in Hashable, Iterable, Iterator, Reversible, Sized, Container, Callable:
class C(B):
pass
self.assertTrue(issubclass(C, B))
self.assertFalse(issubclass(int, C))
def test_registration(self):
- for B in Hashable, Iterable, Iterator, Sized, Container, Callable:
+ for B in Hashable, Iterable, Iterator, Reversible, Sized, Container, Callable:
class C:
__hash__ = None # Make sure it isn't hashable by default
self.assertFalse(issubclass(C, B), B.__name__)
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 31930fc..a22d2e6 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -1516,7 +1516,7 @@
m = mro(D, bases)
self.assertEqual(m, [D, c.MutableSequence, c.Sequence,
c.defaultdict, dict, c.MutableMapping,
- c.Mapping, c.Sized, c.Iterable, c.Container,
+ c.Mapping, c.Sized, c.Reversible, c.Iterable, c.Container,
object])
# Container and Callable are registered on different base classes and