Update key generation in IntMap and IntSet tests

Some IntSet and IntMap functions need to check whether the top-level
split is at the sign bit and handle it specially. Generating sets and
maps with all negative or non-negative keys makes it more likely to
cover all cases in property tests.

Author: meooow25

containers-tests/tests/intmap-properties.hs

@@ -272,7 +272,12 @@ main = defaultMain $ testGroup "intmap-properties"
 --------------------------------------------------------------------}
 
 instance Arbitrary a => Arbitrary (IntMap a) where
-  arbitrary = oneof [go arbitrary, go (getLarge <$> arbitrary)]
+  arbitrary = oneof
+    [ go arbitrary
+    , go (getLarge <$> arbitrary)
+    , go (getNonNegative <$> arbitrary)
+    , go (getNegative <$> arbitrary)
+    ]
     where
       go kgen = fromList <$> listOf ((,) <$> kgen <*> arbitrary)
   shrink = fmap fromList . shrink . toAscList

containers-tests/tests/intset-properties.hs

@@ -151,7 +151,12 @@ test_compareSize = do
   Arbitrary, reasonably balanced trees
 --------------------------------------------------------------------}
 instance Arbitrary IntSet where
-  arbitrary = fromList <$> oneof [arbitrary, fmap (fmap getLarge) arbitrary]
+  arbitrary = fromList <$> oneof
+    [ arbitrary
+    , listOf (getLarge <$> arbitrary)
+    , listOf (getNonNegative <$> arbitrary)
+    , listOf (getNegative <$> arbitrary)
+    ]
   shrink = fmap fromList . shrink . toAscList
 
 {--------------------------------------------------------------------