/usr/lib/hugs/packages/QuickCheck/Test/QuickCheck.hs is in libhugs-quickcheck-bundled 98.200609.21-5.4+b3.
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-- |
-- Module : Test.QuickCheck
-- Copyright : (c) Koen Claessen, John Hughes 2001
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
-- Portability : portable
--
-- QuickCheck v.0.2
-- DRAFT implementation; last update 000104.
-- Koen Claessen, John Hughes.
-- This file represents work in progress, and might change at a later date.
--
-----------------------------------------------------------------------------
module Test.QuickCheck
-- testing functions
( quickCheck -- :: prop -> IO ()
, verboseCheck -- :: prop -> IO ()
, test -- :: prop -> IO () -- = quickCheck
, Config(..) -- :: *
, defaultConfig -- :: Config
, check -- :: Config -> prop -> IO ()
-- property combinators
, forAll -- :: Gen a -> (a -> prop) -> prop
, (==>) -- :: Bool -> prop -> prop
-- gathering test-case information
, label -- :: String -> prop -> prop
, collect -- :: Show a => a -> prop -> prop
, classify -- :: Bool -> String -> prop -> prop
, trivial -- :: Bool -> prop -> prop
-- generator combinators
, Gen -- :: * -> * ; Functor, Monad
, elements -- :: [a] -> Gen a
, two -- :: Gen a -> Gen (a,a)
, three -- :: Gen a -> Gen (a,a,a)
, four -- :: Gen a -> Gen (a,a,a,a)
, sized -- :: (Int -> Gen a) -> Gen a
, resize -- :: Int -> Gen a -> Gen a
, choose -- :: Random a => (a, a) -> Gen a
, oneof -- :: [Gen a] -> Gen a
, frequency -- :: [(Int, Gen a)] -> Gen a
, vector -- :: Arbitrary a => Int -> Gen [a]
-- default generators
, Arbitrary(..) -- :: class
, rand -- :: Gen StdGen
, promote -- :: (a -> Gen b) -> Gen (a -> b)
, variant -- :: Int -> Gen a -> Gen a
-- testable
, Testable(..) -- :: class
, Property -- :: *
-- For writing your own driver
, Result(..) -- :: data
, generate -- :: Int -> StdGen -> Gen a -> a
, evaluate -- :: Testable a => a -> Gen Result
)
where
import Prelude
import System.Random
import Data.List( group, sort, intersperse )
import Control.Monad( liftM2, liftM3, liftM4 )
infixr 0 ==>
infix 1 `classify`
--------------------------------------------------------------------
-- Generator
newtype Gen a
= Gen (Int -> StdGen -> a)
sized :: (Int -> Gen a) -> Gen a
sized fgen = Gen (\n r -> let Gen m = fgen n in m n r)
resize :: Int -> Gen a -> Gen a
resize n (Gen m) = Gen (\_ r -> m n r)
rand :: Gen StdGen
rand = Gen (\n r -> r)
promote :: (a -> Gen b) -> Gen (a -> b)
promote f = Gen (\n r -> \a -> let Gen m = f a in m n r)
variant :: Int -> Gen a -> Gen a
variant v (Gen m) = Gen (\n r -> m n (rands r !! (v+1)))
where
rands r0 = r1 : rands r2 where (r1, r2) = split r0
generate :: Int -> StdGen -> Gen a -> a
generate n rnd (Gen m) = m size rnd'
where
(size, rnd') = randomR (0, n) rnd
instance Functor Gen where
fmap f m = m >>= return . f
instance Monad Gen where
return a = Gen (\n r -> a)
Gen m >>= k =
Gen (\n r0 -> let (r1,r2) = split r0
Gen m' = k (m n r1)
in m' n r2)
-- derived
choose :: Random a => (a, a) -> Gen a
choose bounds = (fst . randomR bounds) `fmap` rand
elements :: [a] -> Gen a
elements xs = (xs !!) `fmap` choose (0, length xs - 1)
vector :: Arbitrary a => Int -> Gen [a]
vector n = sequence [ arbitrary | i <- [1..n] ]
oneof :: [Gen a] -> Gen a
oneof gens = elements gens >>= id
frequency :: [(Int, Gen a)] -> Gen a
frequency xs = choose (1, tot) >>= (`pick` xs)
where
tot = sum (map fst xs)
pick n ((k,x):xs)
| n <= k = x
| otherwise = pick (n-k) xs
-- general monadic
two :: Monad m => m a -> m (a, a)
two m = liftM2 (,) m m
three :: Monad m => m a -> m (a, a, a)
three m = liftM3 (,,) m m m
four :: Monad m => m a -> m (a, a, a, a)
four m = liftM4 (,,,) m m m m
--------------------------------------------------------------------
-- Arbitrary
class Arbitrary a where
arbitrary :: Gen a
coarbitrary :: a -> Gen b -> Gen b
instance Arbitrary () where
arbitrary = return ()
coarbitrary _ = variant 0
instance Arbitrary Bool where
arbitrary = elements [True, False]
coarbitrary b = if b then variant 0 else variant 1
instance Arbitrary Int where
arbitrary = sized $ \n -> choose (-n,n)
coarbitrary n = variant (if n >= 0 then 2*n else 2*(-n) + 1)
instance Arbitrary Integer where
arbitrary = sized $ \n -> choose (-fromIntegral n,fromIntegral n)
coarbitrary n = variant (fromInteger (if n >= 0 then 2*n else 2*(-n) + 1))
instance Arbitrary Float where
arbitrary = liftM3 fraction arbitrary arbitrary arbitrary
coarbitrary x = coarbitrary (decodeFloat x)
instance Arbitrary Double where
arbitrary = liftM3 fraction arbitrary arbitrary arbitrary
coarbitrary x = coarbitrary (decodeFloat x)
fraction a b c = fromInteger a + (fromInteger b / (abs (fromInteger c) + 1))
instance (Arbitrary a, Arbitrary b) => Arbitrary (a, b) where
arbitrary = liftM2 (,) arbitrary arbitrary
coarbitrary (a, b) = coarbitrary a . coarbitrary b
instance (Arbitrary a, Arbitrary b, Arbitrary c) => Arbitrary (a, b, c) where
arbitrary = liftM3 (,,) arbitrary arbitrary arbitrary
coarbitrary (a, b, c) = coarbitrary a . coarbitrary b . coarbitrary c
instance (Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d)
=> Arbitrary (a, b, c, d)
where
arbitrary = liftM4 (,,,) arbitrary arbitrary arbitrary arbitrary
coarbitrary (a, b, c, d) =
coarbitrary a . coarbitrary b . coarbitrary c . coarbitrary d
instance Arbitrary a => Arbitrary [a] where
arbitrary = sized (\n -> choose (0,n) >>= vector)
coarbitrary [] = variant 0
coarbitrary (a:as) = coarbitrary a . variant 1 . coarbitrary as
instance (Arbitrary a, Arbitrary b) => Arbitrary (a -> b) where
arbitrary = promote (`coarbitrary` arbitrary)
coarbitrary f gen = arbitrary >>= ((`coarbitrary` gen) . f)
--------------------------------------------------------------------
-- Testable
data Result
= Result { ok :: Maybe Bool, stamp :: [String], arguments :: [String] }
nothing :: Result
nothing = Result{ ok = Nothing, stamp = [], arguments = [] }
newtype Property
= Prop (Gen Result)
result :: Result -> Property
result res = Prop (return res)
evaluate :: Testable a => a -> Gen Result
evaluate a = gen where Prop gen = property a
class Testable a where
property :: a -> Property
instance Testable () where
property _ = result nothing
instance Testable Bool where
property b = result (nothing{ ok = Just b })
instance Testable Result where
property res = result res
instance Testable Property where
property prop = prop
instance (Arbitrary a, Show a, Testable b) => Testable (a -> b) where
property f = forAll arbitrary f
forAll :: (Show a, Testable b) => Gen a -> (a -> b) -> Property
forAll gen body = Prop $
do a <- gen
res <- evaluate (body a)
return (argument a res)
where
argument a res = res{ arguments = show a : arguments res }
(==>) :: Testable a => Bool -> a -> Property
True ==> a = property a
False ==> a = property ()
label :: Testable a => String -> a -> Property
label s a = Prop (add `fmap` evaluate a)
where
add res = res{ stamp = s : stamp res }
classify :: Testable a => Bool -> String -> a -> Property
classify True name = label name
classify False _ = property
trivial :: Testable a => Bool -> a -> Property
trivial = (`classify` "trivial")
collect :: (Show a, Testable b) => a -> b -> Property
collect v = label (show v)
--------------------------------------------------------------------
-- Testing
data Config = Config
{ configMaxTest :: Int
, configMaxFail :: Int
, configSize :: Int -> Int
, configEvery :: Int -> [String] -> String
}
quick :: Config
quick = Config
{ configMaxTest = 100
, configMaxFail = 1000
, configSize = (+ 3) . (`div` 2)
, configEvery = \n args -> let s = show n in s ++ [ '\b' | _ <- s ]
}
verbose :: Config
verbose = quick
{ configEvery = \n args -> show n ++ ":\n" ++ unlines args
}
defaultConfig :: Config
defaultConfig = quick
test, quickCheck, verboseCheck :: Testable a => a -> IO ()
test = check quick
quickCheck = check quick
verboseCheck = check verbose
check :: Testable a => Config -> a -> IO ()
check config a =
do rnd <- newStdGen
tests config (evaluate a) rnd 0 0 []
tests :: Config -> Gen Result -> StdGen -> Int -> Int -> [[String]] -> IO ()
tests config gen rnd0 ntest nfail stamps
| ntest == configMaxTest config = do done "OK, passed" ntest stamps
| nfail == configMaxFail config = do done "Arguments exhausted after" ntest stamps
| otherwise =
do putStr (configEvery config ntest (arguments result))
case ok result of
Nothing ->
tests config gen rnd1 ntest (nfail+1) stamps
Just True ->
tests config gen rnd1 (ntest+1) nfail (stamp result:stamps)
Just False ->
putStr ( "Falsifiable, after "
++ show ntest
++ " tests:\n"
++ unlines (arguments result)
)
where
result = generate (configSize config ntest) rnd2 gen
(rnd1,rnd2) = split rnd0
done :: String -> Int -> [[String]] -> IO ()
done mesg ntest stamps =
do putStr ( mesg ++ " " ++ show ntest ++ " tests" ++ table )
where
table = display
. map entry
. reverse
. sort
. map pairLength
. group
. sort
. filter (not . null)
$ stamps
display [] = ".\n"
display [x] = " (" ++ x ++ ").\n"
display xs = ".\n" ++ unlines (map (++ ".") xs)
pairLength xss@(xs:_) = (length xss, xs)
entry (n, xs) = percentage n ntest
++ " "
++ concat (intersperse ", " xs)
percentage n m = show ((100 * n) `div` m) ++ "%"
--------------------------------------------------------------------
-- the end.
|