{-# OPTIONS_GHC -Wall #-}
module Test.QuickCheck.Utils
( isAssociativeBy
, isAssociative
, isCommutableBy
, isCommutable
, isTotalOrder
) where
import Prelude
import Test.QuickCheck
isAssociativeBy :: (Show a,Testable prop)
=> (a -> a -> prop) -> Gen a -> (a -> a -> a) -> Property
isAssociativeBy (=~=) src (#) =
forAll src $ \ a ->
forAll src $ \ b ->
forAll src $ \ c ->
((a # b) # c) =~= (a # (b # c))
isAssociative :: (Arbitrary a,Show a,Eq a) => (a -> a -> a) -> Property
isAssociative = isAssociativeBy (==) arbitrary
isCommutableBy :: (Show a,Testable prop)
=> (b -> b -> prop) -> Gen a -> (a -> a -> b) -> Property
isCommutableBy (=~=) src (#) =
forAll src $ \ a ->
forAll src $ \ b ->
(a # b) =~= (b # a)
isCommutable :: (Arbitrary a,Show a,Eq b) => (a -> a -> b) -> Property
isCommutable = isCommutableBy (==) arbitrary
isTotalOrder :: (Ord a) => a -> a -> Property
isTotalOrder x y =
classify (x > y) "less than" $
classify (x == y) "equals" $
classify (x < y) "greater than" $
x < y || x == y || x > y