code: def test_publish(self, mock_hook):
      operator = PubSubPublishMessageOperator(
          task_id=TASK_ID,
          project_id=TEST_PROJECT,
          topic=TEST_TOPIC,
          messages=TEST_MESSAGES,
      )
  
      operator.execute(None)
      mock_hook.return_value.publish.assert_called_once_with(
          project_id=TEST_PROJECT,
          topic=TEST_TOPIC,
          messages=TEST_MESSAGES,
      )
  
imports: from __future__ import annotations
  from typing import Any
  from unittest import mock
  from google.api_core.gapic_v1.method import DEFAULT
  from google.cloud.pubsub_v1.types import ReceivedMessage
  from airflow.providers.google.cloud.operators.pubsub import PubSubCreateSubscriptionOperator, PubSubCreateTopicOperator, PubSubDeleteSubscriptionOperator, PubSubDeleteTopicOperator, PubSubPublishMessageOperator, PubSubPullOperator
label_desc: Use image node_id 1 for calling the TestPubSubPublishOperator obj's underlying member method code with example usage: obj.test_publish(mock_hook) without return types