[tests][linksdk][watchos] Fix HttpClientHandler tests for CFNetwork/watchOS (#186)

As noted in PR 177 [1] this does not build on watchOS since CFNetwork
is not supported on that platform. Uncaught as the PR bots don't build,
nor run, the tests yet.

[1] https://github.com/xamarin/xamarin-macios/pull/177

tests/linker-ios/link sdk/HttpClientTest.cs

@@ -0,0 +1,154 @@
+using System;
+using System.Net.Http;
+using System.Threading.Tasks;
+#if XAMCORE_2_0
+using Foundation;
+#else
+using MonoTouch.Foundation;
+#endif
+using NUnit.Framework;
+
+namespace LinkSdk.Net.Http {
+
+	[TestFixture]
+	[Preserve (AllMembers = true)]
+	public class HttpClientTest {
+
+		async Task<string> Get (HttpClient client)
+		{
+			return await client.GetStringAsync ("http://xamarin.com");
+		}
+
+		string Get (HttpMessageHandler handler)
+		{
+			using (var client = new HttpClient (handler)) {
+				var get = Get (client);
+				get.Wait ();
+				return get.Result;
+			}
+		}
+
+		[Test]
+		public void ManagedSimple ()
+		{
+			Assert.NotNull (Get (new HttpClientHandler ()), "HttpClientHandler");
+		}
+
+		[Test]
+		public void NSSimple ()
+		{
+			Assert.NotNull (Get (new NSUrlSessionHandler ()), "NSUrlSessionHandler");
+		}
+
+		//[Test]
+		public void CFSimple ()
+		{
+			Assert.NotNull (Get (new CFNetworkHandler ()), "CFNetworkHandler");
+		}
+
+		// same HttpClient and handler doing two simultaneous calls
+		void DualGet (HttpMessageHandler handler)
+		{
+			using (var client = new HttpClient (handler)) {
+				var get1 = Get (client);
+				var get2 = Get (client);
+				get1.Wait ();
+				get2.Wait ();
+			}
+		}
+
+		[Test]
+		public void ManagedDual ()
+		{
+			DualGet (new HttpClientHandler ());
+		}
+
+		[Test]
+		public void NSDual ()
+		{
+			DualGet (new NSUrlSessionHandler ());
+		}
+
+		[Test]
+		public void CFDual ()
+		{
+			DualGet (new CFNetworkHandler ());
+		}
+
+		Task<string> Get302 (HttpClient client)
+		{
+			return Task.Run (async () => await client.GetStringAsync ("https://greenbytes.de/tech/tc/httpredirects/t302loc.asis"));
+		}
+
+		void Get302 (HttpClient client, bool allowRedirect)
+		{
+			var result = Get302 (client);
+			try {
+				result.Wait ();
+				if (!allowRedirect)
+					Assert.Fail ("Redirection *dis*allowed - assert should not be reached");
+				Assert.That (result.Result, Contains.Substring ("You have reached the target"), "true");
+			} catch (AggregateException ae) {
+				if (allowRedirect)
+					Assert.Fail ("Redirection allowed - assert should not be reached {0}", ae);
+				var inner = ae.InnerException;
+				Assert.That (inner is HttpRequestException, "HttpRequestException");
+				Assert.That (inner.Message, Contains.Substring ("302 (Found)"), "302");
+			}
+		}
+
+		[Test]
+		public void Managed302_Allowed ()
+		{
+			var handler = new HttpClientHandler ();
+			handler.AllowAutoRedirect = true;
+			var client = new HttpClient (handler);
+			Get302 (client, allowRedirect: handler.AllowAutoRedirect);
+		}
+
+		[Test]
+		public void Managed302_Disallowed ()
+		{
+			var handler = new HttpClientHandler ();
+			handler.AllowAutoRedirect = false;
+			var client = new HttpClient (handler);
+			Get302 (client, allowRedirect: handler.AllowAutoRedirect);
+		}
+
+		[Test]
+		public void NS302_Allowed ()
+		{
+			var handler = new NSUrlSessionHandler ();
+			handler.AllowAutoRedirect = true;
+			var client = new HttpClient (handler);
+			Get302 (client, allowRedirect: handler.AllowAutoRedirect);
+		}
+
+		[Test]
+		public void NS302_Disallowed ()
+		{
+			var handler = new NSUrlSessionHandler ();
+			handler.AllowAutoRedirect = false;
+			var client = new HttpClient (handler);
+			Get302 (client, allowRedirect: handler.AllowAutoRedirect);
+		}
+
+		[Test]
+		public void CF302_Allowed ()
+		{
+			var handler = new CFNetworkHandler ();
+			handler.AllowAutoRedirect = true;
+			var client = new HttpClient (handler);
+			Get302 (client, allowRedirect: handler.AllowAutoRedirect);
+		}
+
+		[Test]
+		public void CF302_Disallowed ()
+		{
+			var handler = new CFNetworkHandler ();
+			handler.AllowAutoRedirect = false;
+			var client = new HttpClient (handler);
+			Get302 (client, allowRedirect: handler.AllowAutoRedirect);
+		}
+	}
+}