code: def test_save_unsupported_mode(tmp_path):
      out = str(tmp_path / "temp.dds")
      im = hopper("HSV")
      with pytest.raises(OSError):
          im.save(out)
  
imports: from io import BytesIO
  import pytest
  from PIL import DdsImagePlugin, Image
  from .helper import assert_image_equal, assert_image_equal_tofile, hopper
label_desc: Use image node_id 17 for calling a global function with example usage: test_save_unsupported_mode(tmp_path) without return types