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{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module TypeSpec (main, spec) where
import Test.Hspec
import Test.Hspec.QuickCheck (prop)
import qualified Test.QuickCheck as QC
import Network.MPD.Commands.Types (Volume)
main :: IO ()
main = hspec spec
spec :: Spec
spec = do
describe "Volume arithmetic is closed over 0-100" $ do
prop "for addition" prop_volume_add
prop "for subtraction" prop_volume_sub
prop "for multiplication" prop_volume_mul
prop "for division" prop_volume_div
instance QC.Arbitrary Volume where
arbitrary = QC.elements [0..100]
inRange :: Ord a => a -> a -> a -> Bool
inRange l h x = l <= x && x <= h
prop_volume_arith op cur new = inRange 0 100 ((cur :: Volume) `op` new)
prop_volume_add = prop_volume_arith (+)
prop_volume_sub = prop_volume_arith (-)
prop_volume_mul = prop_volume_arith (*)
prop_volume_div cur new = new /= 0 QC.==> prop_volume_arith div cur new
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