[tests] Adjust a few tests to try network requests multiple times. (x…

…amarin#14943)

* A few tests seem to be failing rather consistently with network errors.
  Rewrite these tests to try multiple urls before failing (we'll be assuming
  that if one of the urls succeed, the other failures were network related).

* Rename the LinkAnyTest.WebClientTest to LinkAnyTest.WebClientTest_Http to
  follow it's original intent, and make it test http instead of https.

* Remove unnecessary assertion from SSL_IP_5706. This is tested in plenty of other places.

tests/linker/ios/link sdk/CryptoTest.cs

@@ -84,8 +84,6 @@ public void SSL_IP_5706 ()
 			Assert.Ignore ("WatchOS doesn't support BSD sockets, which our network stack currently requires.");
 #endif
 			WebClient wc = new WebClient ();
-			// the certificate contains (several rules) the host name
-			Assert.NotNull (wc.DownloadString (NetworkResources.MicrosoftUrl));
 
 			// IP are (generally) not allowed
 			foreach (var ip in Dns.GetHostAddresses ("www.google.com")) {

tests/linker/ios/link sdk/LinkSdkRegressionTest.cs

@@ -671,10 +671,21 @@ public void WebClient_SSL_Leak ()
 #if __WATCHOS__
 			Assert.Ignore ("WatchOS doesn't support BSD sockets, which our network stack currently requires.");
 #endif
+			var exceptions = new List<string> ();
 			WebClient wc = new WebClient ();
-			// note: needs to be executed under Instrument to verify it does not leak
-			string s = wc.DownloadString (NetworkResources.MicrosoftUrl);
-			Assert.NotNull (s);
+			foreach (var url in NetworkResources.HttpsUrls) {
+				try {
+					// note: needs to be executed under Instrument to verify it does not leak
+					string s = wc.DownloadString (url);
+					Assert.NotNull (s);
+					return; // one url succeeded, that's enough
+				} catch (Exception e) {
+					var msg = $"Url '{url}' failed: {e.ToString ()}";
+					Console.WriteLine (msg); // If this keeps occurring locally for the same url, we might have to take it off the list of urls to test.
+					exceptions.Add (msg);
+				}
+			}
+			Assert.That (exceptions, Is.Empty, "At least one url should work");
 		}
 
 #if !__TVOS__ && !__WATCHOS__ && !__MACOS__

tests/linker/mac/LinkAnyTest.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Net;
 using System.Net.Http;
 using System.Security.Cryptography;
@@ -63,22 +64,35 @@ public void GetWebPageAsyncTest ()
 			}
 		}
 
-		[Test]
-		public void WebClientTest ()
+		void WebClientTest (string[] urls)
 		{
-			var wc = new WebClient ();
-			var data = wc.DownloadString (NetworkResources.MicrosoftUrl);
+			var exceptions = new List<string> ();
+			foreach (var url in urls) {
+				try {
+					var wc = new WebClient ();
+					var data = wc.DownloadString (url);
+
+					Assert.That (data, Is.Not.Empty, "Downloaded content");
+					return; // one url succeeded, that's enough
+				} catch (Exception e) {
+					var msg = $"Url '{url}' failed: {e.ToString ()}";
+					Console.WriteLine (msg); // If this keeps occurring locally for the same url, we might have to take it off the list of urls to test.
+					exceptions.Add (msg);
+				}
+			}
+			Assert.That (exceptions, Is.Empty, "At least one url should work");
+		}
 
-			Assert.That (data, Is.Not.Empty, "Downloaded content");
+		[Test]
+		public void WebClientTest_Http ()
+		{
+			WebClientTest (NetworkResources.HttpUrls);
 		}
 
 		[Test]
 		public void WebClientTest_Https ()
 		{
-			var wc = new WebClient ();
-			var data = wc.DownloadString (NetworkResources.MicrosoftUrl);
-
-			Assert.That (data, Is.Not.Empty, "Downloaded content");
+			WebClientTest (NetworkResources.HttpsUrls);
 		}
 
 		[Test]
@@ -91,15 +105,26 @@ public void WebClientTest_Async ()
 
 				string data = null;
 
-				async Task GetWebPage (string url)
-				{
-					var wc = new WebClient ();
-					var task = wc.DownloadStringTaskAsync (new Uri (url));
-					data = await task;
+				var exceptions = new List<string> ();
+				foreach (var url in NetworkResources.HttpsUrls) {
+					try {
+						async Task GetWebPage (string url)
+						{
+							var wc = new WebClient ();
+							var task = wc.DownloadStringTaskAsync (new Uri (url));
+							data = await task;
+						}
+
+						GetWebPage (url).Wait ();
+						Assert.That (data, Is.Not.Empty, "Downloaded content");
+						return; // one url succeeded, that's enough
+					} catch (Exception e) {
+						var msg = $"Url '{url}' failed: {e.ToString ()}";
+						Console.WriteLine (msg); // If this keeps occurring locally for the same url, we might have to take it off the list of urls to test.
+						exceptions.Add (msg);
+					}
 				}
-
-				GetWebPage (NetworkResources.MicrosoftUrl).Wait ();
-				Assert.That (data, Is.Not.Empty, "Downloaded content");
+				Assert.That (exceptions, Is.Empty, "At least one url should work");
 			} finally {
 				SynchronizationContext.SetSynchronizationContext (current_sc);
 

tests/monotouch-test/System.Net.Http/NetworkResources.cs

@@ -9,12 +9,20 @@ public static class NetworkResources
 	{
 		public static readonly string MicrosoftUrl = "https://www.microsoft.com";
 		public static readonly Uri MicrosoftUri = new Uri (MicrosoftUrl);
+		public static readonly string MicrosoftHttpUrl = "http://www.microsoft.com";
 		public static readonly string XamarinUrl = "https://dotnet.microsoft.com/apps/xamarin";
+		public static readonly string XamarinHttpUrl = "http://dotnet.microsoft.com/apps/xamarin";
 		public static readonly Uri XamarinUri = new Uri (XamarinUrl);
 		public static readonly string StatsUrl = "https://api.imgur.com/2/stats";
 
-		public static readonly string [] Urls = {
+		public static readonly string [] HttpsUrls = {
 			MicrosoftUrl,
+			XamarinUrl,
+		};
+
+		public static readonly string [] HttpUrls = {
+			MicrosoftHttpUrl,
+			XamarinHttpUrl,
 		};
 
 		// Robots urls, useful when we want to get a small file