[tests] Capture the logging service output for our tests

This will make it possible to figure out what is going on
when tests fail.

Author: alanmcgovern

main/tests/UnitTests/TestBase.cs

@@ -40,7 +40,20 @@ public class TestBase
 	{
 		static bool firstRun = true;
 
-		
+		static TestBase ()
+		{
+			var topPath = LocateTopLevel ();
+			LoggingService.AddLogger (new MonoDevelop.Core.Logging.FileLogger (Path.Combine (topPath, "TestResult_LoggingService.log")));
+		}
+
+		static string LocateTopLevel ()
+		{
+			var cwd = typeof (TestBase).Assembly.Location;
+			while (!string.IsNullOrEmpty (cwd) && !File.Exists (Path.Combine (cwd, "top_level_monodevelop")))
+				cwd = Path.GetDirectoryName (cwd);
+			return cwd;
+		}
+
 		[TestFixtureSetUp]
 		public void Simulate ()
 		{

top_level_monodevelop

@@ -0,0 +1,2 @@
+This file exists only to make sure our test suite can locate the top level of the checkout
+