def METHOD_NAME(self, invalid_separator):
    args = self._get_default_args()
    args["-s"] = invalid_separator
    completed_process = self.run_example(args=args, expected_return_code=1)
    assert (
        "ERROR: Allowed separators are single characters which are not alphanumeric and not ',', '.', ':', '-'"
        in completed_process.stdout
    )