From 08f26e2f4458e2b9cbc30eab9f5fdd0b0b44b248 Mon Sep 17 00:00:00 2001 From: Michael Orlitzky Date: Mon, 17 Apr 2017 10:41:03 -0400 Subject: [PATCH] Add a bunch of tests for our weird CIDR order. --- src/Cidr.hs | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 77 insertions(+), 2 deletions(-) diff --git a/src/Cidr.hs b/src/Cidr.hs index 007e94b..9ed146a 100644 --- a/src/Cidr.hs +++ b/src/Cidr.hs @@ -65,6 +65,19 @@ instance Eq Cidr where cidr1 == cidr2 = (cidr1 <= cidr2) && (cidr2 <= cidr1) instance Ord Cidr where + -- | The CIDR order is simply numeric, with the IPv4Address being + -- considered first, before the mask. There was an arbitrary + -- choice that had to be made here: which CIDR is smaller, + -- 127.0.0.1/8, or 127.0.0.1/32? + -- + -- The arguments for 127.0.0.1/8 <= 127.0.0.1/32 are that it + -- agrees with the numeric sort order on masks, and that it's + -- generally nicer to see the big networks before the small ones. + -- + -- On the other hand, this order disagrees with the containment + -- partial order, since 127.0.0.1/32 is contained properly in + -- 127.0.0.1/8. + -- cidr1 <= cidr2 = if addr1 == addr2 then mask1 <= mask2 else addr1 <= addr2 where Cidr addr1 mask1 = normalize cidr1 @@ -296,7 +309,8 @@ cidr_tests = test_combine_all3, test_normalize1, test_normalize2, - test_normalize3 ] + test_normalize3, + test_big_networks_come_first ] cidr_properties :: TestTree cidr_properties = @@ -308,7 +322,11 @@ cidr_properties = prop_ord_instance_antisymmetric, prop_ord_instance_reflexive, prop_ord_instance_transitive, - prop_ord_uses_addr_when_masks_equal ] + prop_ord_uses_addr_when_masks_equal, + prop_ord_uses_mask_when_addrs_equal, + prop_ord_and_contains_disagree, + prop_ord_minimum, + prop_ord_maximum ] -- HUnit Tests @@ -529,6 +547,18 @@ test_normalize3 = expected = read "10.10.8.0/22" :: Cidr actual = normalize (read "10.10.10.10/22" :: Cidr) +-- | Test a stated property of the Ord instance, namely that the big +-- network 127.0.0.1/8 comes before the small network 127.0.0.1/32. +test_big_networks_come_first :: TestTree +test_big_networks_come_first = + testCase desc $ actual @?= expected + where + desc = "127.0.0.1/8 comes before 127.0.0.1/32" + big = read "127.0.0.1/8" :: Cidr + small = read "127.0.0.1/32" :: Cidr + expected = True + actual = big <= small -- not a typo + -- QuickCheck Tests prop_all_cidrs_contain_themselves :: TestTree prop_all_cidrs_contain_themselves = @@ -609,3 +639,48 @@ prop_ord_uses_addr_when_masks_equal = where (Cidr addr1 mask1) = normalize cidr1 (Cidr addr2 mask2) = normalize cidr2 + + +-- If we have two CIDRs whose normalized addresses agree, then we want +-- to use the mask order, i.e. that big networks come before small +-- networks. This disagrees with containment order. +prop_ord_uses_mask_when_addrs_equal :: TestTree +prop_ord_uses_mask_when_addrs_equal = + localOption (QuickCheckTests 500) $ + testProperty "The CIDR order is by mask when the addresses agree" prop + where + prop :: Cidr -> Cidr -> Property + prop cidr1 cidr2 = + (addr1 == addr2) ==> (cidr1 <= cidr2) == (mask1 <= mask2) + where + (Cidr addr1 mask1) = normalize cidr1 + (Cidr addr2 mask2) = normalize cidr2 + + +-- Big networks come first. +prop_ord_and_contains_disagree :: TestTree +prop_ord_and_contains_disagree = + testProperty "The CIDR order disagrees with containment" prop + where + prop :: Cidr -> Cidr -> Property + prop cidr1 cidr2 = (cidr1 `contains` cidr2) ==> (cidr1 <= cidr2) + + +-- The biggest network always comes first. +prop_ord_minimum :: TestTree +prop_ord_minimum = + testProperty "The CIDR order has 0.0.0.0/0 as a minimum" prop + where + min_cidr = read "0.0.0.0/0" :: Cidr + prop :: Cidr -> Bool + prop cidr = min_cidr <= cidr + + +-- The CIDR order also has a maximum. +prop_ord_maximum :: TestTree +prop_ord_maximum = + testProperty "The CIDR order has 255.255.255.255/32 as a maximum" prop + where + max_cidr = read "255.255.255.255/32" :: Cidr + prop :: Cidr -> Bool + prop cidr = max_cidr >= cidr -- 2.44.2