text: from warnings import catch_warnings, simplefilter
  from ..._shared._warnings import expected_warnings
  from ...data import moon
  
  
  def test_filter_import():
      with catch_warnings():
          simplefilter('ignore')
          from skimage import filter as F
  
      assert('sobel' in dir(F))
      assert F._import_warned
  
  
  def test_canny_import():
      data = moon()
      with expected_warnings(['skimage.feature.canny']):
          from skimage.filters import canny
          canny(data)
  