Locate IVsTippingService using COM Guid

Use the COM Guid rather than simple name to locate interface.

Author: jcansdale

src/GitHub.Services.Vssdk/Services/TippingService.cs

@@ -23,6 +23,7 @@ public class TippingService : ITippingService
 
         // This is the only supported ClientId
         public static readonly Guid ClientId = new Guid("D5D3B674-05BB-4942-B8EC-C3D13B5BD6EE");
+        public static readonly Guid IVsTippingServiceGuid = new Guid("756F1DC9-47FA-42C5-9C06-252B54148EB8");
 
         readonly IServiceProvider serviceProvider;
 
@@ -75,7 +76,7 @@ void RequestCalloutDisplay(Guid clientId, Guid calloutId, string title, string m
             var parameterTypes = new Type[] { typeof(Guid), typeof(Guid), typeof(string), typeof(string), typeof(bool),
                 typeof(Microsoft.VisualStudio.OLE.Interop.POINT), typeof(Guid), typeof(uint) };
             var tippingServiceType = tippingService.GetType();
-            var method = tippingService.GetType().GetInterfaces().Where(i => i.Name == "IVsTippingService")
+            var method = tippingService.GetType().GetInterfaces().Where(i => i.GUID == IVsTippingServiceGuid)
                 .FirstOrDefault()?.GetMethod("RequestCalloutDisplay", parameterTypes);
             if (method == null)
             {

test/GitHub.Services.Vssdk.UnitTests/TippingServiceTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.InteropServices;
 using NUnit.Framework;
 using GitHub.Services.Vssdk.Services;
 using NSubstitute;
@@ -49,6 +50,7 @@ public void Check_Arguments_Passed_To_RequestCalloutDisplay()
                 default, commandGroupId, commandId);
         }
 
+        [Guid("756F1DC9-47FA-42C5-9C06-252B54148EB8")]
         public interface IVsTippingService
         {
             void RequestCalloutDisplay(Guid clientId, Guid calloutId, string title, string message, bool isPermanentlyDismissible,