Automatically wait for completion in tests

Tests/EditorTestHelpers/CommandServiceExtensions.cs

@@ -1,8 +1,10 @@
-// Copyright (c) Microsoft. All rights reserved.
+// Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System;
+using System.Threading;
 using Microsoft.VisualStudio.Commanding;
+using Microsoft.VisualStudio.Language.Intellisense.AsyncCompletion;
 using Microsoft.VisualStudio.Text;
 using Microsoft.VisualStudio.Text.Editor;
 using Microsoft.VisualStudio.Text.Editor.Commanding;
@@ -36,11 +38,20 @@ public static void CheckAndExecute<T> (
 			this IEditorCommandHandlerService commandService,
 			Func<ITextView, ITextBuffer, T> argsFactory) where T : EditorCommandArgs
 		{
+			ITextView textView = null;
+			Func<ITextView, ITextBuffer, T> capturingArgsFactory = (v, b) => { textView = v; return argsFactory (v, b); };
 			if (commandService.GetCommandState (argsFactory, Unspecified).IsAvailable) {
-				commandService.Execute (argsFactory, Noop);
+				commandService.Execute (capturingArgsFactory, Noop);
 			} else {
 				throw new InvalidOperationException ($"No handler available for `{typeof (T)}`");
 			}
+
+			//ensure the computation is completed before we continue typing
+			if (textView != null) {
+				if (textView.Properties.TryGetProperty (typeof (IAsyncCompletionSession), out IAsyncCompletionSession session)) {
+					session.GetComputedItems (CancellationToken.None);
+				}
+			}
 		}
 
 		static Action Noop { get; } = new Action (() => { });

Tests/EditorTestHelpers/EditorTestBase.cs

@@ -108,11 +108,6 @@ public async Task TestCommands (
 
 			foreach (var c in commands) {
 				c (commandService);
-
-				//ensure the computation is completed before we continue typing
-				if (textView.Properties.TryGetProperty (typeof (IAsyncCompletionSession), out IAsyncCompletionSession session)) {
-					session.GetComputedItems (CancellationToken.None);
-				}
 			}
 
 			Assert.AreEqual (afterDocumentText, textView.TextBuffer.CurrentSnapshot.GetText ());