-- | The Assertions module contains assertions for use in HUnit
--   tests. They primarily fill the need for an equality test that
--   works with floating point numbers.
--
module Assertions (
  assertAlmostEqual,
  assertTrue )
where

import Control.Monad ( unless )
import Test.Tasty.HUnit (
  Assertion,
  assertBool,
  assertFailure )

import Comparisons ( (~=) )


-- | An HUnit assertion that wraps the almost_equals function. Stolen
--   from the definition of 'assertEqual' in Test\/Tasty\/HUnit\/Orig.hs.
--
assertAlmostEqual :: String -- ^ The message prefix
                  -> Double -- ^ The expected value
                  -> Double -- ^ The actual value
                  -> Assertion
assertAlmostEqual preface expected actual =
  unless (actual ~= expected) (assertFailure msg)
    where msg = (if null preface then "" else preface ++ "\n") ++
                "expected: " ++ show expected ++ "\n but got: " ++ show actual



-- | It's asinine that this doesn't exist already.
--
assertTrue :: String -> Bool -> Assertion
assertTrue = assertBool