如果未引发异常，则通过 Python 单元测试 [英] Pass a Python unittest if an exception isn't raised

问题描述

在 Python unittest 框架中，是否有办法在未引发异常的情况下通过单元测试，否则通过 AssertRaise 失败?

In the Python unittest framework, is there a way to pass a unit test if an exception wasn't raised, and fail with an AssertRaise otherwise?

推荐答案

如果我正确理解你的问题，你可以做这样的事情:

If I understand your question correctly, you could do something like this:

def test_does_not_raise_on_valid_input(self):
    raised = False
    try:
        do_something(42)
    except:
        raised = True
    self.assertFalse(raised, 'Exception raised')

...假设您有相应的测试，可以在无效输入上引发正确的Exception，当然:

...assuming that you have a corresponding test that the correct Exception gets raised on invalid input, of course:

def test_does_raise_on_invalid_input(self):
    self.assertRaises(OutOfCheese, do_something, 43)

然而，正如评论中所指出的，您需要考虑您实际测试的是什么.很可能像这样的测试...

However, as pointed out in the comments, you need to consider what it is that you are actually testing. It's likely that a test like...

def test_what_is_42(self):
    self.assertEquals(do_something(42), 'Meaning of life')

...更好，因为它测试系统所需的行为，如果出现异常就会失败.

...is better because it tests the desired behaviour of the system and will fail if an exception is raised.

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