def test_popitem_removes_some_item_and_returns_it_as_a_key_value_pair(self):
d = ImageDict()
obj1 = cv2.imread(path.join(_this_path, 'data', 'object.png'))
value_1 = 1
d[obj1] = value_1
item_specification = ((obj1, None), value_1)
popped_item = d.popitem()
self.assertEqual(popped_item, item_specification)
self.assertEqual(len(d), 0) #item should have been removed
