code: def test_key_exists(self, mock_service):
      # When
      mock_service.return_value.object_exists.return_value = True
  
      # Given
      res = self.hook.key_exist(MOCK_BUCKET_NAME, MOCK_KEY)
  
      # Then
      assert res is True
      mock_service.assert_called_once_with(MOCK_BUCKET_NAME)
      mock_service.return_value.object_exists.assert_called_once_with(
          MOCK_KEY
      )
  
imports: from __future__ import annotations
  from unittest import mock
  from airflow.providers.alibaba.cloud.hooks.oss import OSSHook
  from tests.providers.alibaba.cloud.utils.oss_mock import mock_oss_hook_default_project_id
label_desc: Use image node_id 17 for calling the TestOSSHook obj's underlying member method code with example usage: obj.test_key_exists(mock_service) without return types