Add JSON (de)serialization test case.

Tests/JSON.hs

@@ -0,0 +1,59 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Tests.JSON where
+import Haste
+import Haste.JSON
+import Haste.Serialize
+import Control.Applicative
+
+data ABC = A | B | C
+  deriving (Show, Read)
+
+data Foo = Foo {
+    string :: String,
+    number :: Int,
+    bool   :: Bool,
+    nested :: Either String Foo,
+    enum   :: ABC
+  } deriving Show
+
+instance Serialize ABC where
+  toJSON = Str . toJSString . show
+  parseJSON (Str s) = case fromJSString s of Just s' -> return $ read s'
+
+instance Serialize Foo where
+  toJSON (Foo s n b nest e) = Dict [
+      ("string", toJSON s),
+      ("number", toJSON n),
+      ("bool", toJSON b),
+      ("nested", toJSON nest),
+      ("enum", toJSON e)
+    ]
+  parseJSON j = Foo <$> j .: "string"
+                    <*> j .: "number"
+                    <*> j .: "bool"
+                    <*> j .: "nested"
+                    <*> j .: "enum"                   
+
+foo :: Foo
+foo = Foo {
+    string = "\"hälsena\"",
+    number = -42,
+    bool   = False,
+    nested = Right (foo {nested = Left "nope"}),
+    enum   = B
+  }
+
+fooStr :: JSString
+fooStr = encodeJSON $ toJSON foo
+
+fooAgain :: Either String Foo
+fooAgain = decodeJSON fooStr >>= fromJSON
+
+runTest :: IO ()
+runTest = do
+  print foo
+  putStrLn ""
+  print fooStr
+  print $ decodeJSON fooStr
+  putStrLn ""
+  print fooAgain