code: def test_cli_env_vars_strategy(_, strategy, monkeypatch, fake_script):
      monkeypatch.setattr(torch.distributed, "run", Mock())
      with pytest.raises(SystemExit) as e:
          _run_model.main([fake_script, "--strategy", strategy])
      assert e.value.code == 0
      assert os.environ["LT_STRATEGY"] == strategy
  
imports: import contextlib
  import os
  import subprocess
  from io import StringIO
  from unittest import mock
  from unittest.mock import Mock
  import pytest
  import torch.distributed.run
  from lightning.fabric.cli import _get_supported_strategies, _run_model
  from lightning_utilities.core.imports import ModuleAvailableCache
  from tests_fabric.helpers.runif import RunIf
label_desc: Use image node_id 4 for calling a global function with example usage: test_cli_env_vars_strategy(_, strategy, monkeypatch, fake_script) without return types