Diff.hs

{-# LANGUAGE BangPatterns #-}

-- |
-- Module      : Test.Amazonka.Diff
-- Copyright   : (c) 2013-2023 Brendan Hay
-- License     : Mozilla Public License, v. 2.0.
-- Maintainer  : Brendan Hay <brendan.g.hay+amazonka@gmail.com>
-- Stability   : provisional
-- Portability : non-portable (GHC extensions)
module Test.Amazonka.Diff where

import System.IO
import System.IO.Temp
import System.Process
import Text.Groom

-- | Display the difference between two Haskell values,
-- with control over the diff parameters.
diff :: (Show a, Show b) => a -> b -> IO String
diff e a =
  withSystemTempFile "diff_expect" $ \ep eh ->
    withSystemTempFile "diff_actual" $ \ap ah -> do
      hPutStrLn eh (groom e) >> hClose eh
      hPutStrLn ah (groom a) >> hClose ah
      (_, !out, !err) <-
        readProcessWithExitCode "diff" ["-U", "3", ep, ap] []
      return (out ++ "\n" ++ err)