code: def test_start_server_find_free_port(uvicorn_mock, tmpdir):
      lightning.app.frontend.web._start_server(
          serve_dir=tmpdir, host="myhost"
      )
      assert uvicorn_mock.run.call_args_list[0].kwargs["port"] > 0
  
file_path: pytorch-lightning/tests/tests_app/frontend/test_web.py
imports: import os
  from unittest import mock
  from unittest.mock import ANY, MagicMock
  import lightning.app
  import pytest
  from lightning.app import LightningFlow
  from lightning.app.frontend.web import StaticWebFrontend, _healthz
  from lightning.app.storage.path import _storage_root_dir
label_desc: Use image node_id 5 for calling a global function with example usage: test_start_server_find_free_port(uvicorn_mock, tmpdir) without return types