code: def test_unknown_pixel_mode(self):
      with pytest.raises(OSError):
          with Image.open("Tests/images/hopper_unknown_pixel_mode.tif"):
              pass
  
imports: import os
  from io import BytesIO
  import pytest
  from PIL import Image, ImageFile, TiffImagePlugin
  from PIL.TiffImagePlugin import RESOLUTION_UNIT, X_RESOLUTION, Y_RESOLUTION
  from .helper import assert_image_equal, assert_image_equal_tofile, assert_image_similar, assert_image_similar_tofile, hopper, is_pypy, is_win32
label_desc: Use image node_id 23 for calling the TestFileTiff obj's underlying member method code with example usage: obj.test_unknown_pixel_mode() without return types