python单元测试中的assertRaises未捕获异常
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/25047256/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
assertRaises in python unit-test not catching the exception
提问by user3014653
Can somebody tell me why the following unit-test is failing on the ValueError in test_bad, rather than catching it with assertRaises and succeeding? I think I'm using the correct procedure and syntax, but the ValueError is not getting caught.
有人能告诉我为什么下面的单元测试在 test_bad 的 ValueError 上失败，而不是用 assertRaises 捕获它并成功吗？我想我使用了正确的过程和语法，但是 ValueError 没有被捕获。
I'm using Python 2.7.5 on a linux box.
我在 linux 机器上使用 Python 2.7.5。
Here is the code …
这是代码……
import unittest
class IsOne(object):
def __init__(self):
pass
def is_one(self, i):
if (i != 1):
raise ValueError
class IsOne_test(unittest.TestCase):
def setUp(self):
self.isone = IsOne()
def test_good(self):
self.isone.is_one(1)
self.assertTrue(True)
def test_bad(self):
self.assertRaises(ValueError, self.isone.is_one(2))
if __name__ == "__main__":
unittest.main()
and here is the output of the unit-test:
这是单元测试的输出：
======================================================================
ERROR: test_bad (__main__.IsOne_test)
----------------------------------------------------------------------
Traceback (most recent call last):
File "test/raises.py", line 20, in test_bad
self.assertRaises(ValueError, self.isone.is_one(2))
File "test/raises.py", line 8, in is_one
raise ValueError
ValueError
----------------------------------------------------------------------
Ran 2 tests in 0.008s
FAILED (errors=1)
回答by Gerrat
Unittest's assertRaisestakes a callable and arguments, so in your case, you'd call it like:
Unittest 的assertRaises需要一个可调用对象和参数，因此在您的情况下，您可以这样称呼它：
self.assertRaises(ValueError, self.isone.is_one, 2)
If you prefer, as of Python2.7, you could also use it as a context manager like:
如果您愿意，从 Python2.7 开始，您还可以将其用作上下文管理器，例如：
with self.assertRaises(ValueError):
self.isone.is_one(2)
