import Prelude hiding (catch)
import System.IO
import System.IO.Unsafe.GetContents
import GHC.Handle
import Control.Exception

test name k = do
  putStrLn $ "  " ++ name
  putStrLn . (replicate 4 ' '++) =<<
    (fmap show (evaluate =<< k)
    `catch` (\e -> return $ "error: " ++ show (e :: SomeException)))

tests hGetC = do
  test "Length OK" $ do
    h <- openFile "testhgetcontents.hs" ReadMode
    xs <- hGetC h
    return $ length xs
  test "Length but closed" $ do
    h <- openFile "testhgetcontents.hs" ReadMode
    xs <- hGetC h
    hClose h
    return $ length xs
  test "Lengths on Double get" $ do
    h <- openFile "testhgetcontents.hs" ReadMode
    xs <- hGetC h
    ys <- hGetC h
    let l1 = length xs
    l1 `seq` return (l1, length ys)
  test "Lengths on dupped get" $ do
    h <- openFile "testhgetcontents.hs" ReadMode
    duph <- hDuplicate h
    xs <- hGetC h
    ys <- hGetC duph
    let l1 = length xs
    l1 `seq` return (l1, length ys)

main = do
  putStrLn "using hGetContents"
  tests hGetContents
  putStrLn "using unsafeHGetContents"
  tests unsafeHGetContents