On Tue, Dec 15, 2009 at 5:56 PM, Serdar Tumgoren <zstumgo...@gmail.com> wrote: > Hi everyone, > > To continue on the popular topic of unit tests, I was wondering if > it's generally preferable to use a single unit test or a series of > unit tests when testing against a regex pattern. > > In my specific case, I started out with a single test that contained a > (growing) list of bad input data intended to fail when tried against a > regex pattern. > > But then I started thinking: Isn't each unit test supposed to test one > thing and one thing only? So I broke up my list of inputs and devoted > a single unit test to each (see below for both of my iterations). > > On the one hand, I can see the benefit of having individual unit tests > for each of these varying inputs, since I can then see precisely which > one failed when I run my tests. > > On the other hand, this one-test-per-pattern seems like a bit of > overkill given that I built up this list of bad inputs sequentially. > In other words, I added the first bad input to my initial list (in > "testIDFormat"), then ran the tests; then I added another failing > input and ran the tests; and so on. > > In that way, I figured I could gradually build up a list of known bad > inputs, and simply append any new bad inputs that crop up later on. > > So my question -- in this particular case involving a regex, what > downsides are there of simply lumping all the known bad values into a > single unit test?
I often use a list of test cases to drive a single test. Using a series of tests is just too painful compared to making a simple list of test cases. The disadvantages to using a list of test cases: - it will die at the first failure, which may hide other failures - the default failure messages are generally not helpful - they won't necessarily tell you which test case failed. I usually build a custom failure message and use the assertXxx() method that takes a message parameter. (In your case, you will have to use a try / catch with a fail() in the try block because assertRaises() doesn't take a msg parameter.) Some of the alternate test runners (nose, py.test) may have better support for this style of testing but it works OK in unittest. Kent _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
