code: def test_execute_with_ack_messages(self, mock_hook):
      operator = PubSubPullOperator(
          task_id=TASK_ID,
          project_id=TEST_PROJECT,
          subscription=TEST_SUBSCRIPTION,
          ack_messages=True,
      )
  
      generated_messages = self._generate_messages(5)
      generated_dicts = self._generate_dicts(5)
      mock_hook.return_value.pull.return_value = generated_messages
  
      assert generated_dicts == operator.execute({})
      mock_hook.return_value.acknowledge.assert_called_once_with(
          project_id=TEST_PROJECT,
          subscription=TEST_SUBSCRIPTION,
          messages=generated_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 4 for calling the TestPubSubPullOperator obj's underlying member method code with example usage: obj.test_execute_with_ack_messages(mock_hook) without return types