Unit testing with QuickCheck

haskell-course.cabal

cabal-version:      2.4
name:               haskell-course
version:            0.1.0.0
maintainer:         web@bennypowers.com
author:             Benny Powers
extra-source-files: CHANGELOG.md

test-suite min-max-test
    type:             exitcode-stdio-1.0
    main-is:          Spec.hs
    hs-source-dirs:   tests
    default-language: Haskell2010
    build-depends:
        base,
        sort,
        hspec,
        QuickCheck

Spec.hs

module Main where

import           Data.Sort
import           Test.Hspec
import           Test.QuickCheck

prop_abs :: Int -> Bool
prop_abs n = abs n == n || 0 - abs n == n

prop_min :: [Int] -> Bool
prop_min l
  | null l = True
  | otherwise = minimum l == head (sort l)

prop_max :: [Int] -> Bool
prop_max l
  | null l = True
  | otherwise = maximum l == last (sort l)


main :: IO ()
main = hspec $ do
  describe "Bounds" $
    do it "gets the minimum" $ property prop_min
       it "gets the maximum" $ property prop_max
  describe "Absolute" $
       it "removes the sign" $ property prop_abs