test_abc.py 文件源码

def test_isinstance_invalidation(self):
        class A(metaclass=abc.ABCMeta):
            pass
        class B:
            pass
        b = B()
        self.assertFalse(isinstance(b, A))
        self.assertFalse(isinstance(b, (A,)))
        token_old = abc.get_cache_token()
        A.register(B)
        token_new = abc.get_cache_token()
        self.assertNotEqual(token_old, token_new)
        self.assertTrue(isinstance(b, A))
        self.assertTrue(isinstance(b, (A,)))