Hello Café,

I am using quicheck for some kind of non trivial tests.

The general form of these tesst is summarized by the following code.

-- Function to be tested. Given a list of splitting functions, split the given list
process :: [a] -> [[a] -> [a]] -> [a]
process l splitFuns =
    List.foldl proc l splitFuns
    where
    proc l splitFun = splitFun l

-- a split function generator
splitFunGen :: Gen ([a] -> [a])
splitFunGen = return $ proc
                where
                proc l = let splitPos = List.length l `div` 2 -- Problem I would like splitPos = some random value between [0 and length of l]
                      in fst $ List.splitAt splitPos l

splitFunsGen :: Gen [[a] -> [a]]
splitFunsGen = vectorOf 20 splitFunGen

instance Show a => Show ([a] -> [a]) where
    show _ = " a split fun "

r = quickCheck $ forAll splitFunsGen prop
    where
    prop splitFuns = let l = process [1..100] splitFuns
                    in List.length l >= 0 -- dummy test here for the sake of example

The process to be tested takes a list that is randomly perturbated (spitFuns). The result of each perturbation is fed into the next perturbation.

Ideally I would like the perturbating function to depend on the previous perturbated list (see computation of splitPos in splitFunGen).

I am not sure how I could use quickcheck in this case.

Has anyone a better idea?

Thanks

J-C