Add test for intersection

Author: sjakobi

Data/HashMap/Internal.hs

@@ -110,10 +110,10 @@ module Data.HashMap.Internal
 
       -- * Debugging
     , valid
-    , Validity
-    , Error
+    , Validity(..)
+    , Error(..)
     , SubHash
-    , SubHashPath
+    , SubHashPath(..)
 
       -- ** Internals used by the strict version
     , Hash

tests/Properties/HashMapLazy.hs

@@ -35,6 +35,7 @@ import Test.Tasty.QuickCheck    (testProperty)
 import qualified Data.Foldable   as Foldable
 import qualified Data.List       as List
 import qualified Test.QuickCheck as QC
+import qualified Data.HashMap.Internal as HMI
 
 #if defined(STRICT)
 import           Data.HashMap.Strict (HashMap)
@@ -87,7 +88,8 @@ mask :: Int
 mask = sum [bit n | n <- [0, 3, 8, 14, 61]]
 
 instance (Eq k, Hashable k, Arbitrary k, Arbitrary v) => Arbitrary (HashMap k v) where
-  arbitrary = fmap (HM.fromList) arbitrary
+  arbitrary = HM.fromList <$> arbitrary
+  shrink = fmap HM.fromList . shrink . HM.toList
 
 keyToInt :: Key -> Int
 keyToInt (K h x) = h * fromEnum x
@@ -365,6 +367,9 @@ pIntersection xs ys =
     `eq_` HM.intersection (HM.fromList xs)
     $ ys
 
+pIntersectionValid :: HashMap Key () -> HashMap Key () -> Property
+pIntersectionValid x y = HMI.valid (HM.intersection x y) === HMI.Valid
+
 pIntersectionWith :: [(Key, Int)] -> [(Key, Int)] -> Property
 pIntersectionWith xs ys = M.intersectionWith (-) (M.fromList xs) `eq_`
                           HM.intersectionWith (-) (HM.fromList xs) $ ys
@@ -575,6 +580,7 @@ tests =
       [ testProperty "difference" pDifference
       , testProperty "differenceWith" pDifferenceWith
       , testProperty "intersection" pIntersection
+      , testProperty "intersection produces valid HashMap" pIntersectionValid
       , testProperty "intersectionWith" pIntersectionWith
       , testProperty "intersectionWithKey" pIntersectionWithKey
       ]