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{-# OPTIONS_GHC -fno-warn-orphans #-}
{-# LANGUAGE AllowAmbiguousTypes #-}
module Spec.Wrapper (
lawsMonoid
)
where
import Barbies (AllBF, ApplicativeB, Barbie(..), ConstraintsB)
import Test.Tasty(testGroup, TestTree)
import Test.Tasty.QuickCheck(Arbitrary(..), testProperty)
lawsMonoid
:: forall b
. ( Arbitrary (b []), Eq (b []), Show (b [])
, ApplicativeB b
, ConstraintsB b
, AllBF Semigroup [] b
, AllBF Monoid [] b
)
=> TestTree
lawsMonoid
= testGroup "Monoid laws"
[ testProperty "neutral element" $ \b ->
unwrap (Barbie b <> mempty) == b &&
unwrap (mempty <> Barbie b) == b
, testProperty "associativity" $ \b1 b2 b3 ->
unwrap ((Barbie b1 <> Barbie b2) <> Barbie b3) ==
unwrap ( Barbie b1 <> (Barbie b2 <> Barbie b3))
]
where
unwrap = getBarbie :: Barbie b [] -> b []
instance Arbitrary (b f) => Arbitrary (Barbie b f) where
arbitrary = Barbie <$> arbitrary
|
