@given(start_action_message_dicts, integers(min_value=2))
    def test_invalid_task_level_in_start_message(self, start_message_dict, i):
        new_level = start_message_dict[TASK_LEVEL_FIELD].append(i)
        message_dict = start_message_dict.set(TASK_LEVEL_FIELD, new_level)
        message = written_from_pmap(message_dict)
        self.assertRaises(
            InvalidStartMessage, WrittenAction.from_messages, message)
All messages in an action have a task level. The first message in an
dataset/ETHPy150Open ClusterHQ/eliot/eliot/tests/test_action.py/WrittenActionTests.test_invalid_task_level_in_start_message