new_contents: import pytest
  import cv2
  import numpy as np
  from plantcv.plantcv import fill
  
  
  def test_fill(test_data):
      # Read in test data
      img = cv2.imread(test_data.small_bin_img, -1)
      fill_img = fill(bin_img=img, size=63632)
      # Assert the image is blank
      assert np.sum(fill_img) == 0
  
  
  def test_fill_bad_input(test_data):
      # Read in test data
      img = cv2.imread(test_data.small_gray_img, -1)
      with pytest.raises(RuntimeError):
          _ = fill(bin_img=img, size=1)
  
subject: Add fill tests module