{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE MagicHash #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Test.QuickCheck.Classes
( primProps
, storableProps
, semigroupProps
, monoidProps
, showReadProps
, jsonProps
, eqProps
#if MIN_VERSION_QuickCheck(2,10,0)
, functorProps
, applicativeProps
, monadProps
#endif
) where
import Test.QuickCheck
import Data.Primitive hiding (sizeOf,newArray,copyArray)
import Data.Primitive.PrimArray
import Data.Proxy
import Control.Monad.ST
import Control.Monad
import Data.Monoid (Endo(..))
import GHC.Ptr (Ptr(..))
import Data.Primitive.Addr (Addr(..))
import Foreign.Marshal.Alloc
import System.IO.Unsafe
import Data.Semigroup (Semigroup)
import GHC.Exts (fromList,toList)
import Foreign.Marshal.Array
import Foreign.Storable
import Text.Read (readMaybe)
import Data.Aeson (FromJSON(..),ToJSON(..))
import Data.Functor.Classes
import Control.Applicative
import qualified Data.Aeson as AE
import qualified Data.Primitive as P
import qualified Data.Semigroup as SG
import qualified GHC.OldList as L
#if MIN_VERSION_QuickCheck(2,10,0)
import Test.QuickCheck.Arbitrary (Arbitrary1(..))
#endif
jsonProps :: (ToJSON a, FromJSON a, Show a, Arbitrary a, Eq a) => Proxy a -> [(String,Property)]
jsonProps p =
[ ("Encoding Equals Value", jsonEncodingEqualsValue p)
, ("Partial Isomorphism", jsonEncodingPartialIsomorphism p)
]
showReadProps :: (Show a, Read a, Eq a, Arbitrary a) => Proxy a -> [(String,Property)]
showReadProps p =
[ ("Partial Isomorphism", showReadPartialIsomorphism p)
]
-- | Tests the following properties:
--
-- [/Associative/]
-- @a <> (b <> c) ≡ (a <> b) <> c@
semigroupProps :: (Semigroup a, Eq a, Arbitrary a, Show a) => Proxy a -> [(String,Property)]
semigroupProps p =
[ ("Associative", semigroupAssociative p)
]
-- | Tests the following properties:
--
-- [/Transitive/]
-- @a == b ∧ b == c ⇒ a == c@
-- [/Symmetric/]
-- @a == b ⇒ b == a@
--
-- Some of these properties involve implication. In the case that
-- the left hand side of the implication arrow does not hold, we
-- do not retry. Consequently, these properties only end up being
-- useful when the data type has a small number of inhabitants.
eqProps :: (Eq a, Arbitrary a, Show a) => Proxy a -> [(String,Property)]
eqProps p =
[ ("Transitive", eqTransitive p)
, ("Symmetric", eqSymmetric p)
]
-- | Tests the following properties:
--
-- [/Associative/]
-- @mappend a (mappend b c) ≡ mappend (mappend a b) c@
-- [/Left Identity/]
-- @mappend mempty a ≡ a@
-- [/Right Identity/]
-- @mappend a mempty ≡ a@
monoidProps :: (Monoid a, Eq a, Arbitrary a, Show a) => Proxy a -> [(String,Property)]
monoidProps p =
[ ("Associative", monoidAssociative p)
, ("Left Identity", monoidLeftIdentity p)
, ("Right Identity", monoidRightIdentity p)
]
primProps :: (Prim a, Eq a, Arbitrary a, Show a) => Proxy a -> [(String,Property)]
primProps p =
[ ("ByteArray Set-Get (you get back what you put in)", primSetGetByteArray p)
, ("ByteArray Get-Set (putting back what you got out has no effect)", primGetSetByteArray p)
, ("ByteArray Set-Set (setting twice is same as setting once)", primSetSetByteArray p)
, ("ByteArray List Conversion Roundtrips", primListByteArray p)
, ("Addr Set-Get (you get back what you put in)", primSetGetAddr p)
, ("Addr Get-Set (putting back what you got out has no effect)", primGetSetAddr p)
, ("Addr List Conversion Roundtrips", primListAddr p)
]
storableProps :: (Storable a, Eq a, Arbitrary a, Show a) => Proxy a -> [(String,Property)]
storableProps p =
[ ("Set-Get (you get back what you put in)", storableSetGet p)
, ("Get-Set (putting back what you got out has no effect)", storableGetSet p)
, ("List Conversion Roundtrips", storableList p)
]
showReadPartialIsomorphism :: forall a. (Show a, Read a, Arbitrary a, Eq a) => Proxy a -> Property
showReadPartialIsomorphism _ = property $ \(a :: a) ->
readMaybe (show a) == Just a
-- TODO: improve the quality of the error message if
-- something does not pass this test.
jsonEncodingEqualsValue :: forall a. (ToJSON a, Show a, Arbitrary a) => Proxy a -> Property
jsonEncodingEqualsValue _ = property $ \(a :: a) ->
case AE.decode (AE.encode a) of
Nothing -> False
Just (v :: AE.Value) -> v == toJSON a
jsonEncodingPartialIsomorphism :: forall a. (ToJSON a, FromJSON a, Show a, Eq a, Arbitrary a) => Proxy a -> Property
jsonEncodingPartialIsomorphism _ = property $ \(a :: a) ->
AE.decode (AE.encode a) == Just a
eqTransitive :: forall a. (Show a, Eq a, Arbitrary a) => Proxy a -> Property
eqTransitive _ = property $ \(a :: a) b c -> case a == b of
True -> case b == c of
True -> a == c
False -> a /= c
False -> case b == c of
True -> a /= c
False -> True
eqSymmetric :: forall a. (Show a, Eq a, Arbitrary a) => Proxy a -> Property
eqSymmetric _ = property $ \(a :: a) b -> case a == b of
True -> b == a
False -> b /= a
semigroupAssociative :: forall a. (Semigroup a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
semigroupAssociative _ = property $ \(a :: a) b c -> a SG.<> (b SG.<> c) == (a SG.<> b) SG.<> c
monoidAssociative :: forall a. (Monoid a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
monoidAssociative _ = property $ \(a :: a) b c -> mappend a (mappend b c) == mappend (mappend a b) c
monoidLeftIdentity :: forall a. (Monoid a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
monoidLeftIdentity _ = property $ \(a :: a) -> mappend mempty a == a
monoidRightIdentity :: forall a. (Monoid a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
monoidRightIdentity _ = property $ \(a :: a) -> mappend a mempty == a
primListByteArray :: forall a. (Prim a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
primListByteArray _ = property $ \(as :: [a]) ->
as == toList (fromList as :: PrimArray a)
primListAddr :: forall a. (Prim a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
primListAddr _ = property $ \(as :: [a]) -> unsafePerformIO $ do
let len = L.length as
ptr@(Ptr addr#) :: Ptr a <- mallocBytes (len * P.sizeOf (undefined :: a))
let addr = Addr addr#
let go :: Int -> [a] -> IO ()
go !ix xs = case xs of
[] -> return ()
(x : xsNext) -> do
writeOffAddr addr ix x
go (ix + 1) xsNext
go 0 as
let rebuild :: Int -> IO [a]
rebuild !ix = if ix < len
then (:) <$> readOffAddr addr ix <*> rebuild (ix + 1)
else return []
asNew <- rebuild 0
free ptr
return (as == asNew)
primSetGetByteArray :: forall a. (Prim a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
primSetGetByteArray _ = property $ \(a :: a) len -> (len > 0) ==> do
ix <- choose (0,len - 1)
return $ runST $ do
arr <- newPrimArray len
writePrimArray arr ix a
a' <- readPrimArray arr ix
return (a == a')
primGetSetByteArray :: forall a. (Prim a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
primGetSetByteArray _ = property $ \(as :: [a]) -> (not (L.null as)) ==> do
let arr1 = fromList as :: PrimArray a
len = L.length as
ix <- choose (0,len - 1)
arr2 <- return $ runST $ do
marr <- newPrimArray len
copyPrimArray marr 0 arr1 0 len
a <- readPrimArray marr ix
writePrimArray marr ix a
unsafeFreezePrimArray marr
return (arr1 == arr2)
primSetSetByteArray :: forall a. (Prim a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
primSetSetByteArray _ = property $ \(a :: a) (as :: [a]) -> (not (L.null as)) ==> do
let arr1 = fromList as :: PrimArray a
len = L.length as
ix <- choose (0,len - 1)
(arr2,arr3) <- return $ runST $ do
marr2 <- newPrimArray len
copyPrimArray marr2 0 arr1 0 len
writePrimArray marr2 ix a
marr3 <- newPrimArray len
copyMutablePrimArray marr3 0 marr2 0 len
arr2 <- unsafeFreezePrimArray marr2
writePrimArray marr3 ix a
arr3 <- unsafeFreezePrimArray marr3
return (arr2,arr3)
return (arr2 == arr3)
primSetGetAddr :: forall a. (Prim a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
primSetGetAddr _ = property $ \(a :: a) len -> (len > 0) ==> do
ix <- choose (0,len - 1)
return $ unsafePerformIO $ do
ptr@(Ptr addr#) :: Ptr a <- mallocBytes (len * P.sizeOf (undefined :: a))
let addr = Addr addr#
writeOffAddr addr ix a
a' <- readOffAddr addr ix
free ptr
return (a == a')
primGetSetAddr :: forall a. (Prim a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
primGetSetAddr _ = property $ \(as :: [a]) -> (not (L.null as)) ==> do
let arr1 = fromList as :: PrimArray a
len = L.length as
ix <- choose (0,len - 1)
arr2 <- return $ unsafePerformIO $ do
ptr@(Ptr addr#) :: Ptr a <- mallocBytes (len * P.sizeOf (undefined :: a))
let addr = Addr addr#
copyPrimArrayToPtr ptr arr1 0 len
a :: a <- readOffAddr addr ix
writeOffAddr addr ix a
marr <- newPrimArray len
copyPtrToMutablePrimArray marr 0 ptr len
free ptr
unsafeFreezePrimArray marr
return (arr1 == arr2)
storableSetGet :: forall a. (Storable a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
storableSetGet _ = property $ \(a :: a) len -> (len > 0) ==> do
ix <- choose (0,len - 1)
return $ unsafePerformIO $ do
ptr :: Ptr a <- mallocArray len
pokeElemOff ptr ix a
a' <- peekElemOff ptr ix
free ptr
return (a == a')
storableGetSet :: forall a. (Storable a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
storableGetSet _ = property $ \(as :: [a]) -> (not (L.null as)) ==> do
let len = L.length as
ix <- choose (0,len - 1)
return $ unsafePerformIO $ do
ptrA <- newArray as
ptrB <- mallocArray len
copyArray ptrB ptrA len
a <- peekElemOff ptrA ix
pokeElemOff ptrA ix a
res <- arrayEq ptrA ptrB len
free ptrA
free ptrB
return res
storableList :: forall a. (Storable a, Eq a, Arbitrary a, Show a) => Proxy a -> Property
storableList _ = property $ \(as :: [a]) -> unsafePerformIO $ do
let len = L.length as
ptr <- newArray as
let rebuild :: Int -> IO [a]
rebuild !ix = if ix < len
then (:) <$> peekElemOff ptr ix <*> rebuild (ix + 1)
else return []
asNew <- rebuild 0
free ptr
return (as == asNew)
arrayEq :: forall a. (Storable a, Eq a) => Ptr a -> Ptr a -> Int -> IO Bool
arrayEq ptrA ptrB len = go 0 where
go !i = if i < len
then do
a <- peekElemOff ptrA i
b <- peekElemOff ptrB i
if a == b
then go (i + 1)
else return False
else return True
#if MIN_VERSION_QuickCheck(2,10,0)
-- | Tests the following applicative properties:
--
-- [/Identity/]
-- @'fmap' 'id' ≡ 'id'@
-- [/Composition/]
-- @fmap (f . g) ≡ 'fmap' f . 'fmap' g@
-- [/Const/]
-- @(<$) ≡ 'fmap' 'const'@
functorProps :: (Functor f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> [(String,Property)]
functorProps p =
[ ("Identity", functorIdentity p)
, ("Composition", functorComposition p)
, ("Const", functorConst p)
]
-- | Tests the following applicative properties:
--
-- [/Identity/]
-- @'pure' 'id' '<*>' v ≡ v@
-- [/Composition/]
-- @'pure' (.) '<*>' u '<*>' v '<*>' w ≡ u '<*>' (v '<*>' w)@
-- [/Homomorphism/]
-- @'pure' f '<*>' 'pure' x ≡ 'pure' (f x)@
-- [/Interchange/]
-- @u '<*>' 'pure' y ≡ 'pure' ('$' y) '<*>' u@
-- [/LiftA2 (1)/]
-- @('<*>') ≡ 'liftA2' 'id'@
applicativeProps :: (Applicative f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> [(String,Property)]
applicativeProps p =
[ ("Identity", applicativeIdentity p)
, ("Composition", applicativeComposition p)
, ("Homomorphism", applicativeHomomorphism p)
, ("Interchange", applicativeInterchange p)
, ("LiftA2 Part 1", applicativeLiftA2_1 p)
-- todo: liftA2 part 2, we need an equation of two variables for this
]
-- | Tests the following monadic properties:
--
-- [/Left Identity/]
-- @'return' a '>>=' k ≡ k a@
-- [/Right Identity/]
-- @m '>>=' 'return' ≡ m@
-- [/Associativity/]
-- @m '>>=' (\\x -> k x '>>=' h) ≡ (m '>>=' k) '>>=' h@
-- [/Return/]
-- @'pure' ≡ 'return'@
-- [/Ap/]
-- @('<*>') ≡ 'ap'@
monadProps :: (Monad f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> [(String,Property)]
monadProps p =
[ ("Left Identity", monadLeftIdentity p)
, ("Right Identity", monadRightIdentity p)
, ("Associativity", monadAssociativity p)
, ("Return", monadReturn p)
, ("Ap", monadAp p)
]
data Apply f a = Apply { getApply :: f a }
instance (Eq1 f, Eq a) => Eq (Apply f a) where
Apply a == Apply b = eq1 a b
data LinearEquation = LinearEquation
{ linearEquationLinear :: Integer
, linearEquationConstant :: Integer
} deriving (Eq)
data LinearEquationM m = LinearEquationM (m LinearEquation) (m LinearEquation)
runLinearEquation :: Integer -> LinearEquation -> Integer
runLinearEquation x (LinearEquation a b) = a * x + b
runLinearEquationM :: Functor m => LinearEquationM m -> Integer -> m Integer
runLinearEquationM (LinearEquationM e1 e2) i = if odd i
then fmap (runLinearEquation i) e1
else fmap (runLinearEquation i) e2
instance Eq1 m => Eq (LinearEquationM m) where
LinearEquationM a1 b1 == LinearEquationM a2 b2 = eq1 a1 a2 && eq1 b1 b2
showLinear :: Int -> LinearEquation -> ShowS
showLinear _ (LinearEquation a b) = shows a . showString " * x + " . shows b
showLinearList :: [LinearEquation] -> ShowS
showLinearList xs = appEndo $ mconcat
$ [Endo (showChar '[')]
++ L.intersperse (Endo (showChar ',')) (map (Endo . showLinear 0) xs)
++ [Endo (showChar ']')]
instance Show1 m => Show (LinearEquationM m) where
show (LinearEquationM a b) = (\f -> f "")
$ showString "\\x -> if odd x then "
. liftShowsPrec showLinear showLinearList 0 a
. showString " else "
. liftShowsPrec showLinear showLinearList 0 b
instance Arbitrary1 m => Arbitrary (LinearEquationM m) where
arbitrary = liftA2 LinearEquationM arbitrary1 arbitrary1
shrink (LinearEquationM a b) = concat
[ map (\x -> LinearEquationM x b) (shrink1 a)
, map (\x -> LinearEquationM a x) (shrink1 b)
]
instance Arbitrary LinearEquation where
arbitrary = do
(a,b) <- arbitrary
return (LinearEquation (abs a) (abs b))
shrink (LinearEquation a b) =
let xs = shrink (a,b)
in map (\(x,y) -> LinearEquation (abs x) (abs y)) xs
-- this is a quadratic equation
data Equation = Equation Integer Integer Integer
deriving (Eq)
-- This show instance is does not actually provide a
-- way to create an equation. Instead, it makes it look
-- like a lambda.
instance Show Equation where
show (Equation a b c) = "\\x -> " ++ show a ++ " * x ^ 2 + " ++ show b ++ " * x + " ++ show c
instance Arbitrary Equation where
arbitrary = do
(a,b,c) <- arbitrary
return (Equation (abs a) (abs b) (abs c))
shrink (Equation a b c) =
let xs = shrink (a,b,c)
in map (\(x,y,z) -> Equation (abs x) (abs y) (abs z)) xs
runEquation :: Equation -> Integer -> Integer
runEquation (Equation a b c) x = a * x ^ 2 + b * x + c
-- This show instance is intentionally a little bit wrong.
-- We don't wrap the result in Apply since the end user
-- should not be made aware of the Apply wrapper anyway.
instance (Show1 f, Show a) => Show (Apply f a) where
showsPrec p = showsPrec1 p . getApply
instance (Arbitrary1 f, Arbitrary a) => Arbitrary (Apply f a) where
arbitrary = fmap Apply arbitrary1
shrink = map Apply . shrink1 . getApply
functorIdentity :: forall f. (Functor f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
functorIdentity _ = property $ \(Apply (a :: f Integer)) -> eq1 (fmap id a) a
func1 :: Integer -> (Integer,Integer)
func1 i = (div (i + 5) 3, i * i - 2 * i + 1)
func2 :: (Integer,Integer) -> (Bool,Either Ordering Integer)
func2 (a,b) = (odd a, if even a then Left (compare a b) else Right (b + 2))
functorComposition :: forall f. (Functor f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
functorComposition _ = property $ \(Apply (a :: f Integer)) ->
eq1 (fmap func2 (fmap func1 a)) (fmap (func2 . func1) a)
functorConst :: forall f. (Functor f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
functorConst _ = property $ \(Apply (a :: f Integer)) ->
eq1 (fmap (const 'X') a) ('X' <$ a)
applicativeIdentity :: forall f. (Applicative f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
applicativeIdentity _ = property $ \(Apply (a :: f Integer)) -> eq1 (pure id <*> a) a
applicativeComposition :: forall f. (Applicative f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
applicativeComposition _ = property $ \(Apply (u' :: f Equation)) (Apply (v' :: f Equation)) (Apply (w :: f Integer)) ->
let u = fmap runEquation u'
v = fmap runEquation v'
in eq1 (pure (.) <*> u <*> v <*> w) (u <*> (v <*> w))
applicativeHomomorphism :: forall f. (Applicative f, Eq1 f, Show1 f) => Proxy f -> Property
applicativeHomomorphism _ = property $ \(e :: Equation) (a :: Integer) ->
let f = runEquation e
in eq1 (pure f <*> pure a) (pure (f a) :: f Integer)
applicativeInterchange :: forall f. (Applicative f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
applicativeInterchange _ = property $ \(Apply (u' :: f Equation)) (y :: Integer) ->
let u = fmap runEquation u'
in eq1 (u <*> pure y) (pure ($ y) <*> u)
applicativeLiftA2_1 :: forall f. (Applicative f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
applicativeLiftA2_1 _ = property $ \(Apply (f' :: f Equation)) (Apply (x :: f Integer)) ->
let f = fmap runEquation f'
in eq1 (liftA2 id f x) (f <*> x)
monadLeftIdentity :: forall f. (Monad f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
monadLeftIdentity _ = property $ \(k' :: LinearEquationM f) (a :: Integer) ->
let k = runLinearEquationM k'
in eq1 (return a >>= k) (k a)
monadRightIdentity :: forall f. (Monad f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
monadRightIdentity _ = property $ \(Apply (m :: f Integer)) ->
eq1 (m >>= return) m
monadAssociativity :: forall f. (Monad f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
monadAssociativity _ = property $ \(Apply (m :: f Integer)) (k' :: LinearEquationM f) (h' :: LinearEquationM f) ->
let k = runLinearEquationM k'
h = runLinearEquationM h'
in eq1 (m >>= (\x -> k x >>= h)) ((m >>= k) >>= h)
monadReturn :: forall f. (Monad f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
monadReturn _ = property $ \(x :: Integer) ->
eq1 (return x) (pure x :: f Integer)
monadAp :: forall f. (Monad f, Eq1 f, Show1 f, Arbitrary1 f) => Proxy f -> Property
monadAp _ = property $ \(Apply (f' :: f Equation)) (Apply (x :: f Integer)) ->
let f = fmap runEquation f'
in eq1 (ap f x) (f <*> x)
#endif