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GHC 9.14.1 · lts/ghc-9.14.x · 7a6c33e · 2026-10-12

Modulequickcheck-assertions-0.3.0Haskell98

Test.QuickCheck.Assertions

Module provides convenient functions to do some assertions in QuickCheck properties with pretty printed reasons. For example you can do something like that:

module Main where

import Test.Hspec
import Test.Hspec.QuickCheck
import Test.QuickCheck.Assertions
import Test.QuickCheck.Property

someProp :: Int -> Int -> Result
someProp a b = (a ?> b)

someOtherProp :: Double -> Double -> Result
someOtherProp a b = (a ?== b)

main = hspec $ describe "failing test" $ do
  prop "must fail" $ someProp
  prop "must fail again" $ someOtherProp

And receive pretty printed fail message when testing:

failing test
  - must fail FAILED [1]
  - must fail again FAILED [2]

1) failing test must fail FAILED
*** Failed! (after 1 test):
>>>>>>>>>>>>>> the value
0
>>>>>>>>>>>>>> should be greater than value
0
0
0


2) failing test must fail again FAILED
*** Failed! (after 2 tests and 4 shrinks):
>>>>>>>>>>>>>> expected
0.0
>>>>>>>>>>>>>> but got
1.0
0.0
1.0

Ok, not very well printed, but better than nothing.

Contents
  1. Assertions
  2. Reexports
Synopsis

Assertions

Reexports

datadata Result

The result of a single test.

Instances1Testable
  • Testable ResultDefined in QuickCheck-2.19.0.0 · Test.QuickCheck.Property