def test_empty_contents_on_dustbin(self): garbage_list = [ PlasticGarbage("Plastic garbage", True), PaperGarbage("Paper garbage", True), Garbage("House waste garbage") ] dustbin = Dustbin("red") for garbage in garbage_list: dustbin.throw_out_garbage(garbage) dustbin.empty_contents() self.assertEqual(len(dustbin.paper_content), 0) self.assertEqual(len(dustbin.plastic_content), 0) self.assertEqual(len(dustbin.house_waste_content), 0)