code: def test_start_method(_, mp_mock, start_method):
      mp_mock.get_all_start_methods.return_value = [start_method]
      launcher = _MultiProcessingLauncher(
          strategy=Mock(), start_method=start_method
      )
      launcher.launch(function=Mock())
      mp_mock.get_context.assert_called_with(start_method)
      mp_mock.start_processes.assert_called_with(
          ANY,
          args=ANY,
          nprocs=ANY,
          start_method=start_method,
      )
  
file_path: pytorch-lightning/tests/tests_fabric/strategies/launchers/test_multiprocessing.py
imports: from unittest import mock
  from unittest.mock import ANY, Mock
  import pytest
  import torch
  from lightning.fabric.strategies.launchers.multiprocessing import _GlobalStateSnapshot, _MultiProcessingLauncher
  from tests_fabric.helpers.runif import RunIf
label_desc: Use image node_id 3 for calling a global function with example usage: test_start_method(_, mp_mock, start_method) without return types