Issue #24635: Fixed flakiness in test_typing.py.

1 files changed, 14 insertions, 3 deletions

diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index b34007dc22..1461cfbe48 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -436,12 +436,14 @@ class CallableTests(TestCase):
             c()
 
     def test_callable_instance_works(self):
-        f = lambda: None
+        def f():
+            pass
         assert isinstance(f, Callable)
         assert not isinstance(None, Callable)
 
     def test_callable_instance_type_error(self):
-        f = lambda: None
+        def f():
+            pass
         with self.assertRaises(TypeError):
             assert isinstance(f, Callable[[], None])
         with self.assertRaises(TypeError):
@@ -674,7 +676,9 @@ class GenericTests(TestCase):
         T = TypeVar('T')
 
         class Node(Generic[T]):
-            def __init__(self, label: T, left: 'Node[T]' = None, right: 'Node[T]' = None):
+            def __init__(self, label: T,
+                         left: 'Node[T]' = None,
+                         right: 'Node[T]' = None):
                 self.label = label  # type: T
                 self.left = left  # type: Optional[Node[T]]
                 self.right = right  # type: Optional[Node[T]]
@@ -934,8 +938,15 @@ class CollectionsAbcTests(TestCase):
 
     def test_iterable(self):
         assert isinstance([], typing.Iterable)
+        # Due to ABC caching, the second time takes a separate code
+        # path and could fail.  So call this a few times.
+        assert isinstance([], typing.Iterable)
+        assert isinstance([], typing.Iterable)
         assert isinstance([], typing.Iterable[int])
         assert not isinstance(42, typing.Iterable)
+        # Just in case, also test issubclass() a few times.
+        assert issubclass(list, typing.Iterable)
+        assert issubclass(list, typing.Iterable)
 
     def test_iterator(self):
         it = iter([])