tvl-depot/users/grfn/xanthous/test/Xanthous/RandomSpec.hs

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module Xanthous.RandomSpec (main, test) where
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import Test.Prelude
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import Control.Monad.Random
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import Xanthous.Random
import Xanthous.Orphans ()
import qualified Data.Interval as Interval
import Data.Interval (Interval, Extended (Finite), (<=..<=))
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main :: IO ()
main = defaultMain test
test :: TestTree
test = testGroup "Xanthous.Random"
[ testGroup "chooseSubset"
[ testProperty "chooses a subset"
$ \(l :: [Int]) (Positive (r :: Double)) -> randomTest $ do
ss <- chooseSubset r l
pure $ all (`elem` l) ss
]
, testGroup "chooseRange"
[ testProperty "chooses in the range"
$ \(rng :: Interval Int) ->
not (Interval.null rng)
==> randomTest ( do
chooseRange rng >>= \case
Just r -> pure
. counterexample (show r)
$ r `Interval.member` rng
Nothing -> pure $ property Discard
)
, testProperty "nonEmpty range is never empty"
$ \ (lower :: Int) (NonZero diff) -> randomTest $ do
let upper = lower + diff
r <- chooseRange (Finite lower <=..<= Finite upper)
pure $ isJust r
]
]
where
randomTest prop = evalRandT prop . mkStdGen =<< arbitrary