def test_iterating_over_an_ImageDict_provides_a_generator_of_keys_as_image_mask_pairs(self): d = ImageDict() obj1 = cv2.imread(path.join(_this_path, 'data', 'object.png')) mask1 = cv2.imread(path.join(_this_path, 'data', 'object_mask.png')) obj2 = cv2.imread(path.join(_this_path, 'data', 'different_object.png')) d[obj1, mask1] = 1 d[obj2] = 2 keys_specification = [(obj1, mask1), (obj2, None)] keys_by_iter = (key for key in d) keys_by_iterkeys = d.iterkeys() keys_by_keys = d.keys() self.assertItemsEqual(list(keys_by_iter), keys_specification) self.assertItemsEqual(list(keys_by_iterkeys), keys_specification) self.assertItemsEqual(keys_by_keys, keys_specification)