multi-except-0.2.1.0: test/Test/Traversable.hs

{-# LANGUAGE OverloadedLists #-}
{-# LANGUAGE TypeApplications #-}

module Test.Traversable
  ( spec
  ) where

import Test.Hspec

import Control.Applicative.MultiExcept

spec :: Spec
spec = describe "Traversable instance" $ do
  it "Just works™" $
    traverse Just (succeed 3) `shouldBe` Just (succeed @() 3)
  it "leaves errors" $
    traverse Just (throwError 3) `shouldBe` Just (throwError @() 3)
  it "Nothing works™" $
    traverse (const Nothing :: a -> Maybe a) (succeed @() 3) `shouldBe` Nothing