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module Spec where
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import Test.Hspec
import Test.QuickCheck
import Control.Exception (evaluate)
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main :: IO ()
main = hspec $ do
  describe "Prelude.head" $ do
    it "returns the first element of a list" $ do
      head [23 ..] `shouldBe` (23 :: Integer)

    it "returns the first element of an arbitrary list" $
      property $ \x xs -> head (x:xs) == (x :: Integer)

    it "throws an exception if used with an empty list" $ do
      evaluate (head []) `shouldThrow` anyException