Added Pair tests

src/Test/Data/Pair.hs

@@ -1,6 +1,16 @@
-module Properties.Pair where
-import Pair
+{-# LANGUAGE ScopedTypeVariables #-}
+module Test.Data.Pair where
+import Data.Pair
+import Test.Framework
+import Test.Framework.Providers.QuickCheck2
 import Test.QuickCheck
 
-propInversion :: (Eq (p a b), Pair p) => p a b -> Bool
-propInversion p = p == fromTuple (toTuple p)
+testPair :: forall p a b.
+    ( Eq (p a b)
+    , Show (p a b)
+    , Arbitrary (p a b)
+    , Pair p) => p a b -> Test
+testPair _ = testGroup "pair"
+    [ testProperty "indempotence" (\(p::p a b) -> fromTuple (toTuple p) == p)
+    , testProperty "rebuild" (\(p::p a b) -> build (left p) (right p) == p)
+    ]

src/Test/Main.hs

@@ -13,6 +13,7 @@ import Test.Data.Enum
 import Test.Data.Modable
 import Test.Data.Naturals
 import Test.Data.Normalize
+import Test.Data.Pair
 import Test.Data.Zeroed
 
 import Data.DateTime.Gregorian
@@ -30,12 +31,14 @@ tests =
         , testModable (undefined::YMD)
         , testNormal (undefined::YMD)
         , testProperty "no overflow" (\(a::YMD) -> fst (normalize a) == 0)
+        , testPair (undefined::YMD)
         ]
     , testGroup "HMS"
         [ testEnum (undefined::HMS)
         , testCoded (undefined::HMS)
         , testModable (undefined::HMS)
-        , testNormal (undefined::YMD)
+        , testNormal (undefined::HMS)
+        , testPair (undefined::HMS)
         , testProperty "reconstructible" (\(a::HMS) ->
             let (o, b) = normalize a
                 size = succ (maxBound - minBound :: HMS)