Add Hashable test

Doesn't pass as instance Hashable (HashMap k v) violates

    (x == y) ==> hashWithSalt salt x == hashWithSalt salt y

property.

Author: phadej

tests/HashSetProperties.hs

@@ -10,7 +10,7 @@ import Data.Hashable (Hashable(hashWithSalt))
 import qualified Data.List as L
 import qualified Data.HashSet as S
 import qualified Data.Set as Set
-import Test.QuickCheck (Arbitrary)
+import Test.QuickCheck (Arbitrary, Property, (==>), (===))
 import Test.Framework (Test, defaultMain, testGroup)
 import Test.Framework.Providers.QuickCheck2 (testProperty)
 
@@ -40,6 +40,19 @@ pFoldable :: [Int] -> Bool
 pFoldable = (L.sort . Foldable.foldr (:) []) `eq`
             (L.sort . Foldable.foldr (:) [])
 
+pPermutationEq :: [Key] -> [Int] -> Bool
+pPermutationEq xs is = S.fromList xs == S.fromList ys
+  where
+    ys = L.map snd . L.sort . L.zip (is ++ [L.maximum (0:is) + 1..]) $ xs
+
+pHashable :: [Key] -> [Int] -> Int -> Property
+pHashable xs is salt =
+    x == y ==> hashWithSalt salt x === hashWithSalt salt y
+  where
+     ys = L.map snd . L.sort . L.zip (is ++ [L.maximum (0:is) + 1..]) $ xs
+     x = S.fromList xs
+     y = S.fromList ys
+
 ------------------------------------------------------------------------
 -- ** Basic interface
 
@@ -113,9 +126,11 @@ tests =
     -- Instances
       testGroup "instances"
       [ testProperty "==" pEq
+      , testProperty "Permutation ==" pPermutationEq
       , testProperty "/=" pNeq
       , testProperty "Read/Show" pReadShow
       , testProperty "Foldable" pFoldable
+      , testProperty "Hashable" pHashable
       ]
     -- Basic interface
     , testGroup "basic interface"