code: def test_custom_rel_cache_dir(self, pytester: Pytester) -> None:
      rel_cache_dir = os.path.join("custom_cache_dir", "subdir")
      pytester.makeini(
          """
              [pytest]
              cache_dir = {cache_dir}
          """.format(
              cache_dir=rel_cache_dir
          )
      )
      pytester.makepyfile(
          test_errored="def test_error():\n    assert False"
      )
      pytester.runpytest()
      assert pytester.path.joinpath(rel_cache_dir).is_dir()
  
imports: import os
  import shutil
  from pathlib import Path
  from typing import Generator
  from typing import List
  import pytest
  from _pytest.config import ExitCode
  from _pytest.monkeypatch import MonkeyPatch
  from _pytest.pytester import Pytester
  from _pytest.tmpdir import TempPathFactory
label_desc: Use image node_id 9 for calling the TestNewAPI obj's underlying member method code with example usage: obj.test_custom_rel_cache_dir(pytester) without return types