QuickCheck FizzBuzz

fizzbuzz.hs

{-# LANGUAGE TemplateHaskell #-}

import Test.QuickCheck

prop_fizz = forAll inputs (\n -> fizz n == "Fizz")
  where
    inputs = must [ divisibleBy 3
                  , not . divisibleBy 5
                  ]

prop_buzz = forAll inputs (\n -> fizz n == "Buzz")
  where
    inputs = must [ divisibleBy 5
                  , not . divisibleBy 3
                  ]

prop_fizzbuzz = forAll inputs (\n -> fizz n == "FizzBuzz")
  where
    inputs = must [ divisibleBy 3
                  , divisibleBy 5
                  ]

prop_otherwise = forAll inputs (\n -> fizz n == show n)
  where
    inputs = must [ not . divisibleBy 3
                  , not . divisibleBy 5
                  ]

must conds =
  suchThat arbitrary cond
  where
    cond n = and (map ($ n) $ (>1):conds)

fizz :: Integer -> String
fizz i | i `rem` 15 == 0 = "FizzBuzz"
       | i `rem` 3 == 0 = "Fizz"
       | i `rem` 5 == 0 = "Buzz"
       | otherwise = show i

divisibleBy x n = n `rem` x == 0

-- Use quickCheckAll TemplateHaskell generate runTests function .
$(return [])
runTests = $quickCheckAll