new_contents: import pytest
  import cv2
  import numpy as np
  from plantcv.plantcv import erode
  
  
  def test_plantcv_erode(test_data):
      # Read in test data
      img = cv2.imread(test_data.small_bin_img, -1)
      erode_img = erode(gray_img=img, ksize=5, i=1)
      # Assert that the output image has the dimensions of the input image and is binary
      assert img.shape == erode_img.shape and np.array_equal(np.unique(erode_img), np.array([0, 255]))
  
  
  def test_plantcv_erode_small_k(test_data):
      # Read in test data
      img = cv2.imread(test_data.small_bin_img, -1)
      with pytest.raises(ValueError):
          _ = erode(gray_img=img, ksize=1, i=1)
  
subject: Add erode tests module