AtLeastTwoAndUnique.purs

module Test.AtLeastTwoAndUnique (runAtLeastTwoAndUnique) where

import Prelude

import Data.Array (nub)
import Test.StrongCheck (Arbitrary, arbitrary)
import Test.StrongCheck.Gen (suchThat)
import Data.Tuple (Tuple(..))
import Data.Tuple.Nested (uncurry3)

newtype AtLeastTwoAndUnique a = AtLeastTwoAndUnique (Tuple (Tuple a a) (Array a))

runAtLeastTwoAndUnique :: forall a. AtLeastTwoAndUnique a -> { fst :: a, snd :: a, xs :: Array a }
runAtLeastTwoAndUnique (AtLeastTwoAndUnique tuple) = (uncurry3 { fst: _, snd: _, xs: _ }) tuple

instance arbAtLeastTwoAndUnique :: (Arbitrary a, Ord a, Show a) => Arbitrary (AtLeastTwoAndUnique a) where
  arbitrary = AtLeastTwoAndUnique `map` (arbitrary `suchThat` (unique `compose` toArray))
    where
    unique xs = nub xs `eq` xs
    toArray (Tuple (Tuple x1 x2) xs) = x1 : x2 : xs