Ensure the compiler package is loaded for integration tests

src/Compilers/Extension/CompilerPackage.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Reflection;
+using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
 using EnvDTE;
@@ -16,6 +17,7 @@ namespace Roslyn.Compilers.Extension
 {
     [ProvideAutoLoad(UIContextGuids.SolutionExists, PackageAutoLoadFlags.BackgroundLoad)]
     [PackageRegistration(UseManagedResourcesOnly = true, AllowsBackgroundLoading = true)]
+    [Guid("31C0675E-87A4-4061-A0DD-A4E510FCCF97")]
     public sealed class CompilerPackage : AsyncPackage
     {
         public static string RoslynHive = null;

src/VisualStudio/IntegrationTest/TestSetup/IntegrationTestServicePackage.cs

@@ -16,12 +16,21 @@ namespace Microsoft.VisualStudio.IntegrationTest.Setup
     [ProvideAutoLoad(UIContextGuids80.SolutionExists, PackageAutoLoadFlags.BackgroundLoad)]
     public sealed class IntegrationTestServicePackage : AsyncPackage
     {
+        private static readonly Guid s_compilerPackage = new Guid("31C0675E-87A4-4061-A0DD-A4E510FCCF97");
+
         protected override async Task InitializeAsync(CancellationToken cancellationToken, IProgress<ServiceProgressData> progress)
         {
             await base.InitializeAsync(cancellationToken, progress).ConfigureAwait(true);
             await JoinableTaskFactory.SwitchToMainThreadAsync(cancellationToken);
             cancellationToken.ThrowIfCancellationRequested();
 
+            var shell = (IVsShell)await GetServiceAsync(typeof(SVsShell));
+            ErrorHandler.ThrowOnFailure(shell.IsPackageInstalled(s_compilerPackage, out var installed));
+            if (installed != 0)
+            {
+                await ((IVsShell7)shell).LoadPackageAsync(s_compilerPackage);
+            }
+
             IntegrationTestServiceCommands.Initialize(this);
         }
     }