Fix breakage, add more tests

rot13.cabal

@@ -33,5 +33,7 @@ test-suite spec
   build-depends:
     base == 4.*,
     hspec >= 1.3,
+    bytestring,
+    text,
     QuickCheck,
     rot13

src/Codec/Rot13.hs

@@ -60,8 +60,8 @@ class Rot13Bytes a where
 -- | Perform the ROT13 cipher on the given 'Integral' instance (in the sense of 'Rot13').
 rot13int :: Integral a => a -> a
 rot13int x
-  | x - 97 < 26 = 97 + rem (x - 84) 26
-  | x - 65 < 26 = 65 + rem (x - 52) 26
+  | (fromIntegral x :: Word) - 97 < 26 = 97 + rem (x - 84) 26
+  | (fromIntegral x :: Word) - 65 < 26 = 65 + rem (x - 52) 26
   | otherwise   = x
 {-# INLINE rot13int #-}
 {-# SPECIALIZE rot13int :: Word -> Word #-}
@@ -91,7 +91,7 @@ rot13int x
 -- | Perform the ROT13 cipher on the given 'Enum' instance (in the sense of 'Rot13').
 {-# INLINE rot13enum #-}
 rot13enum :: Enum a => a -> a
-rot13enum = toEnum . rot13int . fromEnum
+rot13enum = toEnum . (rot13int :: Int -> Int) . fromEnum
 
 -- | Perform the ROT13 cipher on the given 'Storable' instance bytes to yield a 'BS.ByteString'.
 {-# INLINE rot13stor #-}

test/Spec.hs

@@ -1,20 +1,40 @@
+{-# LANGUAGE OverloadedStrings #-}
 
 module Main
   ( main
   ) where
 
-import Test.Hspec
-import Test.QuickCheck
+import           Test.Hspec
+import           Test.QuickCheck
 
-import Codec.Rot13
+import qualified Data.ByteString    as BS
+import qualified Data.Text          as T
+
+import           Codec.Rot13
 
 main :: IO ()
 main = hspec $ do
   describe "Codec.Rot13" $ do
 
-    it "correctly ciphers the alphabet" $ do
-      rot13 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+    it "correctly ciphers the alphabet (rot13 String)" $ do
+      rot13 ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" :: String)
         `shouldBe` "NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm"
 
-    it "is reversible" $
-      property $ \s -> s == (rot13 . rot13) s
+    it "correctly ciphers the alphabet (rot13 ByteString)" $ do
+      rot13 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+        `shouldBe` ("NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm" :: BS.ByteString)
+
+    it "correctly ciphers the alphabet (rot13 Text)" $ do
+      rot13 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+        `shouldBe` ("NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm" :: T.Text)
+
+    it "is reversible (String)" $
+      property $ \s -> s == (rot13 . rot13 :: String -> String) s
+
+    it "is reversible (ByteString)" $
+      property $ \s -> let s' = BS.pack s
+                        in s' == (rot13 . rot13 :: BS.ByteString -> BS.ByteString) s'
+
+    it "is reversible (Text)" $
+      property $ \s -> let s' = T.pack s
+                        in s' == (rot13 . rot13 :: T.Text -> T.Text) s'