test_descr.py 文件源码

def test_unsubclassable_types(self):
        with self.assertRaises(TypeError):
            class X(types.NoneType):
                pass
        with self.assertRaises(TypeError):
            class X(object, types.NoneType):
                pass
        with self.assertRaises(TypeError):
            class X(types.NoneType, object):
                pass
        class O(object):
            pass
        with self.assertRaises(TypeError):
            class X(O, types.NoneType):
                pass
        with self.assertRaises(TypeError):
            class X(types.NoneType, O):
                pass

        class X(object):
            pass
        with self.assertRaises(TypeError):
            X.__bases__ = types.NoneType,
        with self.assertRaises(TypeError):
            X.__bases__ = object, types.NoneType
        with self.assertRaises(TypeError):
            X.__bases__ = types.NoneType, object
        with self.assertRaises(TypeError):
            X.__bases__ = O, types.NoneType
        with self.assertRaises(TypeError):
            X.__bases__ = types.NoneType, O