module Golden where
{
    import Data.IORef;
    import Data.ByteString.Builder;
    import Data.ByteString.Lazy.Char8;
    import Test.Tasty;
    import Test.Tasty.Golden;

    accumulate :: Monoid a => ((a -> IO ()) -> IO r) -> IO a;
    accumulate f = do
    {
        ref <- newIORef mempty;
        _ <- f $ \a1 -> modifyIORef ref (\a0 -> mappend a0 a1);
        readIORef ref;
    };

    goldenVsWrite :: TestName -> FilePath -> ((ByteString -> IO ()) -> IO a) -> TestTree;
    goldenVsWrite name path action = goldenVsString name path $ fmap toLazyByteString $ accumulate $ \write -> action (write . lazyByteString);

    goldenVsWriteString :: TestName -> FilePath -> ((String -> IO ()) -> IO a) -> TestTree;
    goldenVsWriteString name path action = goldenVsWrite name path $ \write -> action (write . pack);
}