code: def test_file(self, cloud, fname):
      cloud.gen({fname: "foo contents"})
      fs, fs_path = parse_external_url(cloud.url, cloud.config)
      result = ls_url(str(cloud / fname), fs_config=cloud.config)
      match_files(
          fs,
          result,
          [{"path": fs.join(fs_path, fname), "isdir": False}],
      )
  
imports: import os
  from typing import Dict, Union
  import pytest
  from funcy import first
  from dvc.exceptions import URLMissingError
  from dvc.repo import Repo
  from dvc.repo.ls_url import ls_url, parse_external_url
  from dvc.utils.fs import remove
label_desc: Use image node_id 1 for calling the TestLsUrl obj's underlying member method code with example usage: obj.test_file(cloud, fname) without return types