test_abc.py 文件源码

def test_descriptors_with_abstractmethod(self):
        class C(metaclass=abc.ABCMeta):
            @property
            @abc.abstractmethod
            def foo(self): return 3
            @foo.setter
            @abc.abstractmethod
            def foo(self, val): pass
        self.assertRaises(TypeError, C)
        class D(C):
            @C.foo.getter
            def foo(self): return super().foo
        self.assertRaises(TypeError, D)
        class E(D):
            @D.foo.setter
            def foo(self, val): pass
        self.assertEqual(E().foo, 3)
        # check that the property's __isabstractmethod__ descriptor does the
        # right thing when presented with a value that fails truth testing:
        class NotBool(object):
            def __nonzero__(self):
                raise ValueError()
            __len__ = __nonzero__
        with self.assertRaises(ValueError):
            class F(C):
                def bar(self):
                    pass
                bar.__isabstractmethod__ = NotBool()
                foo = property(bar)