Unit test adventures - part 1
Published on Tuesday, February 9, 2010 11:28:23 AM UTC in Programming
Dieses Post stammt aus dem ursprünglichen "Mister Goodcat"-Blog bei Geeks with Blogs (2009-2010).
Some days ago I added a feature to an existing application, and when I was testing it, I felt that some calculations in the already existing parts of the software were wrong. After digging through the code I found that an external mathematical library is used, which was developed by a colleague some time ago. Due to its nature (being a pretty basic library), it was well-resourced with unit tests, and a short test run showed all of them succeeding.
I sat down and did some old-school pen and paper calculations, and the results clearly showed that the algorithm in question was way off. I went to see the colleague responsible for the library and it turned out that he found a groundbreaking new technique of creating unit tests that saved him quite some time during the development. Apparently, you just need to follow these three simple rules:
- Write a stub for what you want to test.
- Debug the (failing) test and...
- Put the result of that test run as expected results into the asserts...
Very groundbreaking indeed.