    def test_check_schema_with_different_metaschema_defaults_to_self(self):
        """
        A validator whose metaschema doesn't declare $schema defaults to its
        own validation behavior, not the latest "normal" specification.
        """

        NoEmptySchemasValidator = validators.create(
            meta_schema={"fail": [{"message": "Meta schema whoops!"}]},
            validators={"fail": fail},
        )
        with self.assertRaises(exceptions.SchemaError):
            NoEmptySchemasValidator.check_schema({})
A validator whose metaschema doesn't declare $schema defaults to its
own validation behavior, not the latest "normal" specification.
jsonschema/tests/test_validators.py