code: def test_webcam_resource_warnings():
      """
      Test for issue #697. Ensures that ffmpeg Reader standard streams are
      properly closed by checking for ResourceWarning "unclosed file".
  
      todo: use pytest.does_not_warn() as soon as it becomes available
       (see https://github.com/pytest-dev/pytest/issues/9404)
      """
      try:
          with warnings.catch_warnings(record=True) as warns:
              warnings.simplefilter("error")
              with iio.get_reader("<video0>"):
                  pass
      except IndexError:
          pytest.xfail("no webcam")
  
      if imageio_ffmpeg.__version__ == "0.4.5":
          # We still expect imagio_ffmpeg 0.4.5 to generate (at most) one warning.
          # todo: remove this assertion when a fix for imageio_ffmpeg issue #61
          #  has been released
          assert len(warns) < 2
          return
  
      # There should not be any warnings, but show warning messages if there are.
      assert not [w.message for w in warns]
  
imports: import gc
  import os
  import platform
  import sys
  import threading
  import time
  import warnings
  from io import BytesIO
  from pathlib import Path
  import imageio.plugins
  import imageio.v2
  import imageio.v3
  import numpy
  import pytest
  from imageio import core
  from imageio.core import IS_PYPY
  from conftest import deprecated_test
label_desc: Use image node_id 23 for calling a global function with example usage: test_webcam_resource_warnings() without return types