[mtouch tests] Use a different default app name for service extensions.

Otherwise it might end up clashing with the main app's name, preventing code sharing.

tests/mtouch/MTouch.cs

@@ -421,11 +421,11 @@ namespace Xamarin
 			using (var extension = new MTouchTool ()) {
 				// Create a library with the same name as the root assembly
 				var tmp = extension.CreateTemporaryDirectory ();
-				var dll = CompileTestAppCode ("library", tmp, "public class X {}");
+				var dll = CompileTestAppCode ("library", tmp, "public class X {}", appName: "testApp");
 
 				extension.Linker = MTouchLinker.DontLink; // fastest.
 				extension.Extension = true;
-				extension.CreateTemporararyServiceExtension (extraArg: $"-r:{Quote (dll)}", extraCode: "class Z { static void Y () { System.Console.WriteLine (typeof (X)); } }");
+				extension.CreateTemporararyServiceExtension (extraArg: $"-r:{Quote (dll)}", extraCode: "class Z { static void Y () { System.Console.WriteLine (typeof (X)); } }", appName: "testApp");
 				extension.CreateTemporaryCacheDirectory ();
 				extension.References = new [] { dll };
 				extension.AssertExecute (MTouchAction.BuildSim, "extension build");

tests/mtouch/MTouchTool.cs

@@ -475,10 +475,10 @@ namespace Xamarin
 				File.WriteAllText (Path.Combine (app, "Info.plist"), CreatePlist (Profile, appName));
 		}
 
-		public void CreateTemporararyServiceExtension (string code = null, string extraCode = null, string extraArg = null)
+		public void CreateTemporararyServiceExtension (string code = null, string extraCode = null, string extraArg = null, string appName = "testServiceExtension")
 		{
 			var testDir = CreateTemporaryDirectory ();
-			var app = Path.Combine (testDir, "testApp.appex");
+			var app = Path.Combine (testDir, $"{appName}.appex");
 			Directory.CreateDirectory (app);
 
 			if (code == null) {
@@ -493,7 +493,7 @@ public partial class NotificationService : UNNotificationServiceExtension
 				code += extraCode;
 
 			AppPath = app;
-			RootAssembly = MTouch.CompileTestAppLibrary (testDir, code: code, profile: Profile, extraArg: extraArg);
+			RootAssembly = MTouch.CompileTestAppLibrary (testDir, code: code, profile: Profile, extraArg: extraArg, appName: appName);
 
 			File.WriteAllText (Path.Combine (app, "Info.plist"),
 @"<?xml version=""1.0"" encoding=""UTF-8""?>