Add an antisymmetry property check for the Cidr Ord instance.

[hath.git] / src / Cidr.hs

diff --git a/src/Cidr.hs b/src/Cidr.hs
index d071586036a17cd90bb32c2da6b0eccc14129869..af9c9e8ba55a6c9aaaa5190baf4800599a1623cc 100644 (file)
--- a/src/Cidr.hs
+++ b/src/Cidr.hs
@@ -23,12 +23,13 @@ import Data.List (nub)
 import Data.List.Split (splitOneOf)
 import Data.Maybe (catMaybes, mapMaybe)
 
-import Test.Tasty ( TestTree, testGroup )
+import Test.Tasty ( TestTree, localOption, testGroup )
 import Test.Tasty.HUnit ( (@?=), testCase )
 import Test.Tasty.QuickCheck (
   Arbitrary( arbitrary ),
   Gen,
   Property,
+  QuickCheckTests( QuickCheckTests ),
   (==>),
   testProperty )
 import Text.Read (readMaybe)
@@ -61,12 +62,14 @@ instance Eq Cidr where
   -- | Two CIDRs are equal if they have the same network bits and if
   --   their masks are the same. In other words, if they are the same
   --   after normalization.
-  cidr1 == cidr2 = addr1 == addr2 && mask1 == mask2
+  cidr1 == cidr2 = (cidr1 <= cidr2) && (cidr2 <= cidr1)
+
+instance Ord Cidr where
+  cidr1 <= cidr2 = if addr1 == addr2 then mask1 <= mask2 else addr1 <= addr2
     where
       Cidr addr1 mask1 = normalize cidr1
       Cidr addr2 mask2 = normalize cidr2
 
-
 -- | Returns the mask portion of a CIDR address. That is, everything
 --   after the trailing slash.
 maskbits_from_cidr_string :: String -> Maybe Maskbits
@@ -300,7 +303,11 @@ cidr_properties =
   testGroup "CIDR Properties" [
       prop_all_cidrs_contain_themselves,
       prop_contains_proper_antisymmetric,
-      prop_normalize_idempotent ]
+      prop_normalize_idempotent,
+      prop_normalize_preserves_equality,
+      prop_ord_instance_antisymmetric,
+      prop_ord_instance_reflexive,
+      prop_ord_instance_transitive ]
 
 
 -- HUnit Tests
@@ -545,7 +552,44 @@ prop_contains_proper_antisymmetric =
 -- Running "normalize" a second time shouldn't do anything.
 prop_normalize_idempotent :: TestTree
 prop_normalize_idempotent =
-  testProperty "The CIDR \"normalize\" function is idempotent " prop
+  testProperty "The CIDR \"normalize\" function is idempotent" prop
   where
     prop :: Cidr -> Bool
     prop cidr = (normalize cidr) == (normalize (normalize cidr))
+
+-- Normalization should not affect equality of two CIDRs.
+prop_normalize_preserves_equality :: TestTree
+prop_normalize_preserves_equality =
+  testProperty "The CIDR \"normalize\" function preserves equality" prop
+  where
+    prop :: Cidr -> Cidr -> Bool
+    prop cidr1 cidr2 = (cidr1 == cidr2) == (normalize cidr1 == normalize cidr2)
+
+
+prop_ord_instance_reflexive :: TestTree
+prop_ord_instance_reflexive =
+  testProperty "The CIDR order is reflexive" prop
+  where
+    prop :: Cidr -> Bool
+    prop cidr = cidr <= cidr
+
+
+prop_ord_instance_transitive :: TestTree
+prop_ord_instance_transitive =
+  testProperty "The CIDR order is transitive" prop
+  where
+    prop :: Cidr -> Cidr -> Cidr -> Property
+    prop cidr1 cidr2 cidr3 =
+      (cidr1 <= cidr2 && cidr2 <= cidr3) ==> cidr1 <= cidr3
+
+-- This is how Eq is currently implemented, but it is useful to have
+-- around in case that changes. Try fewer instances of this than usual
+-- because it's a rare condition.
+prop_ord_instance_antisymmetric :: TestTree
+prop_ord_instance_antisymmetric =
+  localOption (QuickCheckTests 500) $
+    testProperty "The CIDR order is antisymmetric" prop
+  where
+    prop :: Cidr -> Cidr -> Property
+    prop cidr1 cidr2 =
+      (cidr1 <= cidr2 && cidr2 <= cidr1) ==> cidr1 == cidr2