[Python-3000] Interaction between unittest and keyword argument machinery (original) (raw)

Collin Winter collinw at gmail.com
Wed Mar 7 16:53:56 CET 2007

On 3/7/07, Patrick Maupin <pmaupin at gmail.com> wrote:

> > Because unittest always creates **kwargs, any code path in a C > > function which is only executed when the *keywords parameter is NULL > > will never be correctly tested from the standard unittest methods. > > This needs some context; which call from unittest to a C function are > you talking about?

Umm, my broken ones? :) In doing some personal doctesting, I noticed an issue in my PEP3101 code with a null pointer, and added a test to the unittest code to catch it in preparation for fixing it. My unittest code never failed, and I realized that the unittest module was always passing down a keyword dictionary, even when no keywords were passed to it. I'm sure that most Python C programmers are more experienced/careful than I am, but even so, it seems that there are a whole class of potential bugs in C functions that unittest cannot check for at present, because it always passes a keywords dictionary.

The only place in unittest that uses **kwargs is TestCase.failUnlessRaises()/assertRaises(); is this the method you're using when writing your tests? If so, then don't use assertRaises(): just call your function and trap the exception manually.

Collin Winter

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