def METHOD_NAME(self):
    self.multicontainer._containerize()
    make_docker_compose_args = self.fs_handler.make_docker_compose.call_args[0]
    actual_env_arg = make_docker_compose_args[0]
    # Optional --envvars has higher priority than ones set through setenv
    self.assertDictEqual({'a': '1', 'b': '2', 'z': '0', 'c': '5'}, actual_env_arg.map)
    self.assertSetEqual(set(), actual_env_arg.to_remove)