code: def test_forking_on_unsupported_platform(_):
      with pytest.raises(
          ValueError,
          match="The start method 'fork' is not available on this platform",
      ):
          _MultiProcessingLauncher(strategy=Mock(), start_method="fork")
  
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 2 for calling a global function with example usage: test_forking_on_unsupported_platform(_) without return types