code: def test_show_no_metrics_files(tmp_dir, dvc, caplog):
      assert dvc.metrics.show() == {"": {"data": {}}}
  
imports: import json
  import os
  from os.path import join
  import pytest
  from funcy import get_in
  from dvc.cli import main
  from dvc.dvcfile import PROJECT_FILE
  from dvc.exceptions import OverlappingOutputPathsError
  from dvc.repo import Repo
  from dvc.utils.fs import remove
  from dvc.utils.serialize import JSONFileCorruptedError
label_desc: Use image node_id 17 for calling a global function with example usage: test_show_no_metrics_files(tmp_dir, dvc, caplog) without return types