class TestStack(unittest.TestCase): def test_flow(self): self.test_stack = Stack() self.test_stack.add_item(10) self.test_stack.add_item(20) self.test_stack.add_item(22, 33) assert self.test_stack.pop_item() == 33 assert self.test_stack.pop_item() == 22 assert self.test_stack.count_items() == 2 while self.test_stack.pop_item(): pass assert self.test_stack.count_items() == 0