code: def test_monochrome(tmp_path):
      # Arrange
      mode = "1"
  
      # Act / Assert
      outfile = helper_save_as_pdf(tmp_path, mode)
      assert os.path.getsize(outfile) < (
          5000 if features.check("libtiff") else 15000
      )
  
imports: from __future__ import annotations
  import io
  import os
  import os.path
  import tempfile
  import time
  import pytest
  from PIL import Image, PdfParser, features
  from .helper import hopper, mark_if_feature_version, skip_unless_feature
label_desc: Use image node_id 5 for calling a global function with example usage: test_monochrome(tmp_path) without return types