1 files changed, 23 insertions, 1 deletions

diff --git a/tests/properties.hs b/tests/properties.hs
index 41950e7..23371ba 100644
--- a/tests/properties.hs
+++ b/tests/properties.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE DeriveGeneric #-}
 module Main (main) where
 
 import Control.Applicative
@@ -6,9 +7,11 @@ import qualified Data.ByteString.Lazy as L
 import Test.Framework (defaultMain)
 import Test.Framework.Providers.QuickCheck2 (testProperty)
 import Test.QuickCheck
+import GHC.Generics
 
 import Data.BEncode
 
+
 instance Arbitrary B.ByteString where
     arbitrary = fmap B.pack arbitrary
 
@@ -19,12 +22,31 @@ instance Arbitrary BEncode where
                 , (5,  BList    <$> (arbitrary `suchThat` ((10 >) . length)))
                 ]
 
+
 prop_EncDec :: BEncode -> Bool
 prop_EncDec x = case decode (L.toStrict (encode x)) of
                   Left _   -> False
                   Right x' -> x == x'
 
+data List a = Cons a (List a) | Nil
+              deriving (Show, Eq, Generic)
+
+instance BEncodable a => BEncodable (List a)
+
+instance Arbitrary a => Arbitrary (List a) where
+  arbitrary = frequency
+    [ (90, pure Nil)
+    , (10, Cons <$> arbitrary <*> arbitrary)
+    ]
+
+data T a = T
+
+prop_bencodable :: Eq a => BEncodable a => T a -> a -> Bool
+prop_bencodable _ x = decoded (L.toStrict (encoded x)) == Right x
+
 main :: IO ()
 main = defaultMain
-       [ testProperty "encode <-> decode" prop_EncDec
+       [ testProperty "encode >>> decode = id" prop_EncDec
+       , testProperty "generic encode >>> decode = id" $
+            prop_bencodable (T :: T (List Int))
        ]
\ No newline at end of file