code: def test_run_cli_success(self, popen_mock):
      proc_mock = mock.MagicMock()
      proc_mock.returncode = 0
      proc_mock.stdout.readline.return_value = b""
      popen_mock.return_value = proc_mock
  
      hook = self.pig_hook()
      stdout = hook.run_cli("")
  
      assert stdout == ""
  
file_path: airflow/tests/providers/apache/pig/hooks/test_pig.py
imports: from __future__ import annotations
  from unittest import mock
  import pytest
  from airflow.providers.apache.pig.hooks.pig import PigCliHook
label_desc: Use image node_id 3 for calling the TestPigCliHook obj's underlying member method code with example usage: obj.test_run_cli_success(popen_mock) without return types