On 4/23/11 8:02 AM, Sönke Hahn wrote:

Hi!

I would like to have a library that would allow to use QuickCheck in the normal manner, but it would save test data for failing properties on the filesystem (maybe using the shiny new acid-state?). On consecutive test runs, the saved test data would be used first (before generating new arbitrary test data). I think, this would come in quite handy when doing test driven development.

Any comments on this? Does something like this already exist?

The closest I can think of is using HUnit on the same property functions you use in QuickCheck. I do this often for regression testing and to ensure that corner cases are covered[1]. Unfortunately this still requires a bit of hand-holding to keep your regression suite up to date. I would *love* there to be a tool which (a) automatically saves failing QuickCheck values to disk, and (b) automates using HUnit to load those in and test them. I'm not so sure that QuickCheck should be doing the second step of that since that'd really mess with the QuickCheck infrastructure; once you have the code for reading from disk, it'd be trivial to just use HUnit. [1] I also do some overloading of (==>) and similar, so that I can use the same properties in both QuickCheck and lazy SmallCheck. Unfortunately, I've yet to come up with a good way to ensure that QuickCheck doesn't explore territory already covered by SmallCheck. -- Live well, ~wren