Environmental fails

quickcheck-file.hs

import Test.QuickCheck
import Test.QuickCheck.Instances.Maybe
import Test.QuickCheck.Monadic

instance Arbitrary LogLevel where
  arbitrary = do
    n <- choose (0, 4) :: Gen Int
    return $ case n of
      0 -> LevelDebug
      1 -> LevelInfo
      2 -> LevelWarn
      3 -> LevelError
      4 -> LevelOther "other"

instance Arbitrary Conf where
  arbitrary = Conf <$> maybeGen nonulls
                   <*> maybeGen arbitrary
                   <*> maybeGen arbitrary
                   <*> maybeGen arbitrary
    where nonempty = getNonEmpty <$> arbitrary
          nonulls = nonempty `suchThat` (not . ('\NUL' `elem`))

testEnvProperties :: TestTree
testEnvProperties = testGroup "(checked by QuickCheck)"
  [ QC.testProperty "Log Level environmental configuration" $
      \(x :: LogLevel) -> Just x == fromVar (toVar x)
  , QC.testProperty "Configuration environmental configuration" $
      \(c :: Conf) -> monadicIO $ do
        res <- run $ do
                  let Conf{..} = c
                      set k v = maybe (unsetEnv k) (\x -> setEnv k $ (unpack . show) x) v
                  set "SKYLARK_CONFFILE" _cConfFile
                  set "SKYLARK_PORT" _cPort
                  set "SKYLARK_TIMEOUT" _cTimeout
                  set "SKYLARK_LOGLEVEL" _cLogLevel
                  decodeEnv
        Test.QuickCheck.Monadic.assert $ res == Right c
  ]

testProperties :: TestTree
testProperties = testGroup "Properties" [ testEnvProperties ]