code: def test_empty_image():
      image = np.zeros((6, 6), dtype=bool)
      with expected_warnings(["entirely zero"]):
          assert_array_equal(convex_hull_image(image), image)
  
file_path: scikit-image/skimage/morphology/tests/test_convex_hull.py
imports: import numpy
  from skimage.morphology import convex_hull_image, convex_hull_object
  from skimage.morphology._convex_hull import possible_hull
  from skimage._shared import testing
  from skimage._shared.testing import assert_array_equal
  from skimage._shared._warnings import expected_warnings
label_desc: Use image node_id 2 for calling a global function with example usage: test_empty_image() without return types