[Python-Dev] unittest missing assertNotRaises (original) (raw)

Steven D'Aprano steve at pearwood.info
Wed Sep 28 01:43:13 CEST 2011

Oleg Broytman wrote:

On Tue, Sep 27, 2011 at 07:46:52PM +0100, Wilfred Hughes wrote:

+ def assertNotRaises(self, excClass, callableObj=None, *args, **kwargs): + """Fail if an exception of class excClass is thrown by + callableObj when invoked with arguments args and keyword + arguments kwargs. + + """ + try: + callableObj(*args, **kwargs) + except excClass: + raise self.failureException("%s was raised" % excClass) + + What if I want to assert my test raises neither OSError nor IOError?

Passing (OSError, IOError) as excClass should do it.

But I can't see this being a useful test. As written, exceptions are still treated as errors, except for excClass, which is treated as a test failure. I can't see the use-case for that. assertRaises is useful:

"IOError is allowed, but any other exception is a bug."

makes perfect sense. assertNotRaises doesn't seem sensible or useful to me:

"IOError is a failed test, but any other exception is a bug."

What's the point? When would you use that?

-- Steven

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