* Janek S.
Cool, looking forward to reading it! Well, the post is already finished: http://ics.p.lodz.pl/~stolarek/blog/2012/10/code-testing-in-haskell/ I was just going to publish it and then your email came up on the list.
I hope you won't forget to cover SmallCheck in your article as well. Being also the maintainer of SmallCheck, I want it to steal some fame from QuickCheck :) Sorry to disappoint you, but I did not mention SmallCheck. So far I'm relying on QuickCheck and didn't feel like I need to look for other testing library. I might be wrong of course.
There are some technical advantages to SmallCheck (determinism, no need to shrink etc.), but the main reason I prefer it is because it gives me more confidence. With quickcheck, I know that it generated 100 tests, but I've no idea what those tests are, and whether the RNG missed some important corner cases. With SmallCheck I know that it tried *all* cases up to certain depth, so it's much more reassuring. (Except for cases when the notion of depth isn't that informative, like floating-point numbers.) Roman