From a8c2d85d8611f7f56eaa0c3406ec423d68f81f96 Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Mon, 17 Apr 2017 08:56:52 -0400
Subject: [PATCH] Add an antisymmetry property check for the Cidr Ord instance.

---
 src/Cidr.hs       | 17 ++++++++++++++++-
 test/TestSuite.hs |  7 +++++--
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/src/Cidr.hs b/src/Cidr.hs
index d7f6246..af9c9e8 100644
--- 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)
@@ -304,6 +305,7 @@ cidr_properties =
       prop_contains_proper_antisymmetric,
       prop_normalize_idempotent,
       prop_normalize_preserves_equality,
+      prop_ord_instance_antisymmetric,
       prop_ord_instance_reflexive,
       prop_ord_instance_transitive ]
 
@@ -563,6 +565,7 @@ prop_normalize_preserves_equality =
     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
@@ -578,3 +581,15 @@ prop_ord_instance_transitive =
     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
diff --git a/test/TestSuite.hs b/test/TestSuite.hs
index 32b81e2..fa39ef3 100644
--- a/test/TestSuite.hs
+++ b/test/TestSuite.hs
@@ -1,6 +1,6 @@
 import Test.Tasty( TestTree, defaultMain, localOption, testGroup )
 import Test.Tasty.QuickCheck(
-  QuickCheckTests( QuickCheckTests),
+  QuickCheckTests( QuickCheckTests ),
   QuickCheckMaxRatio( QuickCheckMaxRatio ))
 import Cidr( cidr_properties, cidr_tests )
 import IPv4Address( ipv4address_properties, ipv4address_tests )
@@ -15,8 +15,11 @@ tests = testGroup "All Tests" [
           octet_properties,
           octet_tests ]
 
+-- | Warning: the QuickCheckMaxRatio option is not a ratio. It's
+--   currently set to \"100%\", so that the test suite passes even if
+--   we have to throw out all of our random test cases.
 main :: IO ()
 main =
   defaultMain $
     localOption (QuickCheckTests 5000) $
-    localOption (QuickCheckMaxRatio 50) tests
+    localOption (QuickCheckMaxRatio 5000) tests
-- 
2.43.2