diff options
Diffstat (limited to 'Lib/test/test_isinstance.py')
-rw-r--r-- | Lib/test/test_isinstance.py | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/Lib/test/test_isinstance.py b/Lib/test/test_isinstance.py index 65751ab916..53639e984e 100644 --- a/Lib/test/test_isinstance.py +++ b/Lib/test/test_isinstance.py @@ -251,6 +251,27 @@ class TestIsInstanceIsSubclass(unittest.TestCase): # blown self.assertRaises(RecursionError, blowstack, isinstance, '', str) + def test_issubclass_refcount_handling(self): + # bpo-39382: abstract_issubclass() didn't hold item reference while + # peeking in the bases tuple, in the single inheritance case. + class A: + @property + def __bases__(self): + return (int, ) + + class B: + def __init__(self): + # setting this here increases the chances of exhibiting the bug, + # probably due to memory layout changes. + self.x = 1 + + @property + def __bases__(self): + return (A(), ) + + self.assertEqual(True, issubclass(B(), int)) + + def blowstack(fxn, arg, compare_to): # Make sure that calling isinstance with a deeply nested tuple for its # argument will raise RecursionError eventually. |