quickCheckAll always return “True”

Question

I\'m trying to use QuickCheck following another answer. I test like this:

{-# LANGUAGE TemplateHaskell #-}
import Test.QuickCheck
import Test.QuickCheck.All

         


        

Answer 1

From the Test.QuickCheck.All docs:

To use quickCheckAll, add a definition to your module along the lines of

return []
runTests = $quickCheckAll

and then execute runTests.

Note: the bizarre return [] in the example above is needed on GHC 7.8; without it, quickCheckAll will not be able to find any of the properties.

Adding return [] before your check makes it work for me.

Answer 2

To use quickCheckAll, you need a function which reads:

return [] runTests = $quickCheckAll

The other comment mentions this, but doesn't point out that it will still always return true unless the function is located below all of your quickCheck functions!