Add tests! 🧪 (property testing)

morse.cabal

@@ -34,7 +34,7 @@ executable morse
 
 test-suite tests
   hs-source-dirs:      tests
-  main-is:             test.hs
+  main-is:             Spec.hs
   ghc-options:         -Wall -fno-warn-orphans
   type:                exitcode-stdio-1.0
   default-language:    Haskell2010

tests/Spec.hs

@@ -0,0 +1,24 @@
+module Main where
+
+import qualified Data.Map        as M
+import           Morse
+import           Test.QuickCheck
+
+allowedChars :: [Char]
+allowedChars = M.keys letterToMorse
+
+allowedMorse :: [Morse]
+allowedMorse = M.elems letterToMorse
+
+charGen :: Gen Char
+charGen = elements allowedChars
+
+morseGen :: Gen Morse
+morseGen = elements allowedMorse
+
+prop_thereAndBackAgain :: Property
+prop_thereAndBackAgain =
+  forAll charGen (\c -> ((charToMorse c) >>= morseToChar) == Just c)
+
+main :: IO ()
+main = quickCheck prop_thereAndBackAgain