[System][tests] Tweak Dns unit tests so it does not fail on an IPv6 only network

Some existing tests only works when IPv4 is available, which was fine as
it match how we historically ran those tests.

Apple has a new requirement [1] to test under an "IPv6 only network" and
the change facilitate this.

[1] https://developer.apple.com/news/?id=05042016a

diff --git a/mcs/class/System/Test/System.Net/DnsTest.cs b/mcs/class/System/Test/System.Net/DnsTest.cs
index fe3769fd5455e49f1795d6cd89d16be27f12fc1a..6487e11784658ff8d6cb1b677432f47a284445b2 100644 (file)
--- a/mcs/class/System/Test/System.Net/DnsTest.cs
+++ b/mcs/class/System/Test/System.Net/DnsTest.cs
@@ -55,8 +55,9 @@ namespace MonoTests.System.Net
 \r
                        IAsyncResult async = Dns.BeginResolve (site1Dot, null, null);\r
                        IPHostEntry entry = Dns.EndResolve (async);\r
-                       SubTestValidIPHostEntry (entry);\r
-                       Assert.AreEqual (site1Dot, entry.AddressList [0].ToString ());\r
+                       SubTestValidIPHostEntry (entry);
+                       var ip = GetNonIPv6Address (entry);\r
+                       Assert.AreEqual (site1Dot, ip.ToString ());\r
                }\r
 \r
                void ResolveCallback (IAsyncResult ar)\r
@@ -205,12 +206,21 @@ namespace MonoTests.System.Net
                        }\r
                }\r
 \r
+               static IPAddress GetNonIPv6Address (IPHostEntry h)\r
+               {\r
+                       var al0 = h.AddressList [0];\r
+                       if (al0.AddressFamily == AddressFamily.InterNetworkV6)\r
+                               Assert.Ignore ("Resolve address is incompatible, e.g. running on an IPv6 only network");\r
+                       return al0;\r
+               }\r
+\r
                void SubTestGetHostByName (string siteName, string siteDot)\r
                {\r
                        IPHostEntry h = Dns.GetHostByName (siteName);\r
                        SubTestValidIPHostEntry (h);\r
                        Assert.AreEqual (siteName, h.HostName, "siteName");\r
-                       Assert.AreEqual (siteDot, h.AddressList [0].ToString (), "siteDot");\r
+                       var ip = GetNonIPv6Address (h);\r
+                       Assert.AreEqual (siteDot, ip.ToString (), "siteDot");\r
                }\r
 \r
                [Test]\r
@@ -287,7 +297,8 @@ namespace MonoTests.System.Net
                        IPAddress addr = new IPAddress (IPAddress.NetworkToHostOrder ((int) site1IP));\r
                        IPHostEntry h = Dns.GetHostByAddress (addr);\r
                        SubTestValidIPHostEntry (h);\r
-                       Assert.AreEqual (addr.ToString (), h.AddressList [0].ToString ());\r
+                       var ip = GetNonIPv6Address (h);\r
+                       Assert.AreEqual (addr.ToString (), ip.ToString ());\r
                }\r
 \r
                [Test]\r
@@ -295,8 +306,9 @@ namespace MonoTests.System.Net
                {\r
                        IPAddress addr = new IPAddress (IPAddress.NetworkToHostOrder ((int) site2IP));\r
                        IPHostEntry h = Dns.GetHostByAddress (addr);\r
-                       SubTestValidIPHostEntry (h);\r
-                       Assert.AreEqual (addr.ToString (), h.AddressList [0].ToString ());\r
+                       SubTestValidIPHostEntry (h);
+                       var ip = GetNonIPv6Address (h);\r
+                       Assert.AreEqual (addr.ToString (), ip.ToString ());\r
                }\r
 \r
                [Test]\r