{-# LANGUAGE ScopedTypeVariables #-}
module Tests.Utils
(
(=^=)
, withRedirect
, withTempFile
) where
import Control.Exception (SomeException, bracket, bracket_, evaluate, try)
import Control.Monad (when)
import Debug.Trace (trace)
import GHC.IO.Handle.Internals (withHandle)
import System.Directory (removeFile)
import System.IO (Handle, hClose, hFlush, hIsOpen, hIsWritable, openTempFile)
import System.IO.Unsafe (unsafePerformIO)
(=^=) :: (Eq a, Show a) => a -> a -> Bool
i =^= j = unsafePerformIO $ do
x <- try (evaluate i)
y <- try (evaluate j)
case (x,y) of
(Left (_ :: SomeException), Left (_ :: SomeException))
-> return True
(Right a, Right b) -> return (a == b)
e -> trace ("*** Divergence: " ++ show e) return False
infix 4 =^=
{-# NOINLINE (=^=) #-}
withTempFile :: (FilePath -> Handle -> IO a) -> IO a
withTempFile = bracket (openTempFile "." "crashy.txt") cleanupTemp . uncurry
where
cleanupTemp (path,h) = do
open <- hIsOpen h
when open (hClose h)
removeFile path
withRedirect :: Handle -> Handle -> IO a -> IO a
withRedirect tmp h = bracket_ swap swap
where
whenM p a = p >>= (`when` a)
swap = do
whenM (hIsOpen tmp) $ whenM (hIsWritable tmp) $ hFlush tmp
whenM (hIsOpen h) $ whenM (hIsWritable h) $ hFlush h
withHandle "spam" tmp $ \tmph -> do
hh <- withHandle "spam" h $ \hh ->
return (tmph,hh)
return (hh,())