Add generic GetServiceAsync to IGitHubServiceProvider

Keep it consistent with GetService<T> and GetService<T, Ret>.
Fix failing VSGitExt unit tests.

Author: jcansdale

src/GitHub.Exports/Services/IGitHubServiceProvider.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Threading.Tasks;
+using System.Diagnostics.CodeAnalysis;
 using System.ComponentModel.Composition.Hosting;
 using System.Runtime.InteropServices;
 using GitHub.VisualStudio;
@@ -30,6 +31,9 @@ Ret GetService<T, Ret>() where T : class
         /// or if it's null, the service will be removed without checking for ownership</param>
         void RemoveService(Type t, object owner);
 
-        Task<object> GetServiceAsync(Type serviceType);
+        Task<T> GetServiceAsync<T>() where T : class;
+
+        [SuppressMessage("Microsoft.Design", "CA1004:GenericMethodsShouldProvideTypeParameter")]
+        Task<Ret> GetServiceAsync<T, Ret>() where T : class where Ret : class;
     }
 }

src/GitHub.TeamFoundation.14/Services/VSGitExt.cs

@@ -96,7 +96,7 @@ async Task ContextChangedAsync()
 
         async Task<bool> TryInitialize()
         {
-            gitService = (IGitExt)await serviceProvider.GetServiceAsync(typeof(IGitExt));
+            gitService = await serviceProvider.GetServiceAsync<IGitExt>();
             if (gitService != null)
             {
                 gitService.PropertyChanged += (s, e) =>

src/GitHub.VisualStudio/Services/GitHubServiceProvider.cs

@@ -72,7 +72,9 @@ public IServiceProvider GitServiceProvider
 
         public T TryGetService<T>() where T : class => theRealProvider.TryGetService<T>();
 
-        public Task<object> GetServiceAsync(Type serviceType) => theRealProvider.GetServiceAsync(serviceType);
+        public Task<T> GetServiceAsync<T>() where T : class => theRealProvider.GetServiceAsync<T>();
+
+        public Task<Ret> GetServiceAsync<T, Ret>() where T : class where Ret : class => theRealProvider.GetServiceAsync<T, Ret>();
     }
 
     /// <summary>
@@ -312,6 +314,7 @@ public void Dispose()
             GC.SuppressFinalize(this);
         }
 
-        public Task<object> GetServiceAsync(Type serviceType) => asyncServiceProvider.GetServiceAsync(serviceType);
+        public async Task<T> GetServiceAsync<T>() where T : class => (T)await asyncServiceProvider.GetServiceAsync(typeof(T));
+        public async Task<Ret> GetServiceAsync<T, Ret>() where T : class where Ret : class => (Ret)await asyncServiceProvider.GetServiceAsync(typeof(T));
     }
 }

test/UnitTests/GitHub.TeamFoundation/VSGitExtTests.cs

@@ -25,7 +25,7 @@ public void GetServiceIGitExt_WhenSccProviderContextIsActive(bool isActive, int
 
             var target = CreateVSGitExt(context, sp: sp);
 
-            sp.Received(expectCalls).GetService<IGitExt>();
+            sp.Received(expectCalls).GetServiceAsync<IGitExt>();
         }
 
         [TestCase(true, 1)]
@@ -39,7 +39,7 @@ public void GetServiceIGitExt_WhenUIContextChanged(bool activated, int expectCal
             var eventArgs = new VSUIContextChangedEventArgs(activated);
             context.UIContextChanged += Raise.Event<EventHandler<VSUIContextChangedEventArgs>>(context, eventArgs);
 
-            sp.Received(expectCalls).GetService<IGitExt>();
+            sp.Received(expectCalls).GetServiceAsync<IGitExt>();
         }
 
         [Test]
@@ -218,7 +218,7 @@ static VSGitExt CreateVSGitExt(IVSUIContext context = null, IGitExt gitExt = nul
         var contextGuid = new Guid(Guids.GitSccProviderId);
         factory.GetUIContext(contextGuid).Returns(context);
         sp.GetService<IVSUIContextFactory>().Returns(factory);
-        sp.GetService<IGitExt>().Returns(gitExt);
+        sp.GetServiceAsync<IGitExt>().Returns(gitExt);
         var vsGitExt = new VSGitExt(sp, factory, repoFactory);
         vsGitExt.PendingTasks.Wait();
         return vsGitExt;