diff --git a/Lib/os.py b/Lib/os.py index 52d3f1d7415854e..253cad1a59f35ad 100644 --- a/Lib/os.py +++ b/Lib/os.py @@ -26,6 +26,8 @@ import sys import stat as st +from _collections_abc import _check_methods + _names = sys.builtin_module_names # Note: more names are added to __all__ later. @@ -1070,7 +1072,9 @@ def __fspath__(self): @classmethod def __subclasshook__(cls, subclass): - return hasattr(subclass, '__fspath__') + if cls is PathLike: + return _check_methods(subclass, '__fspath__') + return NotImplemented if name == 'nt': diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py index 4a076e3bbf5426b..11454b2e88ff65a 100644 --- a/Lib/test/test_os.py +++ b/Lib/test/test_os.py @@ -4017,6 +4017,14 @@ def test_bad_pathlike(self): self.assertRaises(ZeroDivisionError, self.fspath, FakePath(ZeroDivisionError())) + def test_pathlike_subclasshook(self): + # bpo-38878: subclasshook causes subclass checks + # true on abstract implementation. + class A(os.PathLike): + pass + self.assertFalse(issubclass(FakePath, A)) + self.assertTrue(issubclass(FakePath, os.PathLike)) + class TimesTests(unittest.TestCase): def test_times(self): diff --git a/Misc/NEWS.d/next/Library/2019-11-22-12-08-52.bpo-38878.EJ0cFf.rst b/Misc/NEWS.d/next/Library/2019-11-22-12-08-52.bpo-38878.EJ0cFf.rst new file mode 100644 index 000000000000000..9cbdf08dd53e318 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-11-22-12-08-52.bpo-38878.EJ0cFf.rst @@ -0,0 +1,2 @@ +Fixed __subclasshook__ of :class:`os.PathLike` to return a correct result +upon inheritence. Patch by Bar Harel.