code: def test_fio_ls_single_layer(data_dir):
      result = CliRunner().invoke(main_group, ["ls", data_dir])
      assert result.exit_code == 0
      assert len(result.output.splitlines()) == 1
      assert sorted(json.loads(result.output)) == [
          "coutwildrnp",
          "gre",
          "test_tin",
      ]
  
file_path: Fiona/tests/test_fio_ls.py
imports: import json
  import sys
  import os
  from click.testing import CliRunner
  import pytest
  import fiona
  from fiona.fio.main import main_group
label_desc: Use image node_id 1 for calling a global function with example usage: test_fio_ls_single_layer(data_dir) without return types