code: def test_dev_null(resources):
      if "COV_CORE_DATAFILE" in os.environ:
          pytest.skip("Coverage uses stdout")
  
      p = run_ocrmypdf(
          resources / "trivial.pdf",
          os.devnull,
          "--force-ocr",
          "--plugin",
          "tests/plugins/tesseract_noop.py",
      )
      assert p.returncode == 0, "could not send output to /dev/null"
      assert len(p.stdout) == 0, "wrote to stdout"
  
file_path: OCRmyPDF/tests/test_stdio.py
imports: from __future__ import annotations
  import os
  from subprocess import DEVNULL, PIPE, run
  import pytest
  from ocrmypdf.helpers import check_pdf
  from .conftest import run_ocrmypdf
label_desc: Use image node_id 3 for calling a global function with example usage: test_dev_null(resources) without return types