如何使用assertRises（）引发错误

Question

我正在学习如何在Python中使用unittest进行单元测试。我想做的是在转数为负的情况下引发ValueError并显示一条消息，例如“转弯不能为负”。

我到目前为止编写的代码如下：

import unittest
from canvas import Game


class TestPlayer1(unittest.TestCase):

    def setUp(self):

        # Game objects
        self.game_turn_0 = Game()
        self.game_turn_5 = Game()
        self.game_turn_negative = Game()

        # values
        self.game_turn_0.turn = 0
        self.game_turn_5.turn = 5
        self.game_turn_negative = -2

    def test_get_turn(self):
        self.assertEqual(self.game_turn_0.get_turn(), 0)
        self.assertEqual(self.game_turn_5.get_turn(), 5)
        with self.assertRaises(ValueError):
            print('value error!')


if __name__ == '__main__':
    unittest.main()

但是结果与预期不符，如您所见：

Testing started at 09:55 ...
C:\Users\oricc\PycharmProjects\practisingDrowing\venv\Scripts\python.exe "C:\Program Files\JetBrains\PyCharm Community Edition 2019.2.3\helpers\pycharm\_jb_unittest_runner.py" --target test_canvas.TestPlayer1.test_get_turn
Launching unittests with arguments python -m unittest test_canvas.TestPlayer1.test_get_turn in C:\Users\oricc\PycharmProjects\practisingDrowing

pygame 1.9.6
Hello from the pygame community. https://www.pygame.org/contribute.html
value error!

Failure
Traceback (most recent call last):
  File "C:\Users\oricc\AppData\Local\Programs\Python\Python37-32\lib\unittest\case.py", line 59, in testPartExecutor
    yield
  File "C:\Users\oricc\AppData\Local\Programs\Python\Python37-32\lib\unittest\case.py", line 628, in run
    testMethod()
  File "C:\Users\oricc\PycharmProjects\practisingDrowing\test_canvas.py", line 23, in test_get_turn
    print('value error!')
  File "C:\Users\oricc\AppData\Local\Programs\Python\Python37-32\lib\unittest\case.py", line 203, in __exit__
    self._raiseFailure("{} not raised".format(exc_name))
  File "C:\Users\oricc\AppData\Local\Programs\Python\Python37-32\lib\unittest\case.py", line 135, in _raiseFailure
    raise self.test_case.failureException(msg)
AssertionError: ValueError not raised


Assertion failed

Assertion failed


Ran 1 test in 0.034s

FAILED (failures=1)

Process finished with exit code 1

Assertion failed

Assertion failed

Assertion failed

Assertion failed

到目前为止，我已经观看了一些视频，阅读了python website上的文档，并阅读了一些帖子。我就可以掌握。

我的意思是，我无法在自己的情况下使用它。

有人可以向我解释这是如何工作的吗？谢谢

Answer 1

Class TestPlayer1（unittest.TestCase）：

def setUp(self):

    # Game objects
    self.game_turn_0 = Game()
    self.game_turn_5 = Game()
    self.game_turn_negative = Game()

    # values
    self.game_turn_0.turn = 0
    self.game_turn_5.turn = 5
    self.game_turn_negative = -2

def test_get_turn(self):
    self.assertEqual(self.game_turn_0.get_turn(), 0)
    self.assertEqual(self.game_turn_5.get_turn(), 5)
    with self.assertRaises(ValueError):
        print('value error!')

如果名称 =='主'：unittest.main（）