Class MyMapping

Lib/test/test_collections.py:1848–1854

            self.assertIsSubclass(sample, Mapping)
        self.validate_abstract_methods(Mapping, '__iter__', '__len__', '__getitem__')
        class MyMapping(Mapping):
            def __len__(self):
                return 0
            def __getitem__(self, i):
                raise IndexError
            def __iter__(self):
                return iter(())
        self.validate_comparison(MyMapping())
        self.assertRaises(TypeError, reversed, MyMapping())