While Visual Studio's VSIX Installer automatically installs nested VSIX references (which is the method by which the MEF services extensions are delivered), the Visual Studio SDK will not perform this installation automatically in the experimental instance. After launching the experimental instance for the first time (or after you reset it), you will need to install the VSBase Services Debugging Support extension from the Visual Studio Gallery and restart the experimental instance before your extension will work.

Note
Future releases of individual extensions may improve support in this area by updating the .targets file included in the implementation to automatically deploy the nested VSIX extension(s) to the experimental instance for debugging purposes. Stay tuned!

Special steps are required to ensure that Visual Studio will be able to locate utility library assemblies at runtime. The specific configuration steps to take depend on the minimum version of Visual Studio your extension will support.

Note
These configuration steps should be performed in the project that creates your VSIX extension, even if another assembly actually references the utility library.

1. Regardless of the version of Visual Studio you are supporting, you need to make sure your extension is configured to generate a pkgdef file. Open your extension's project file in an XML editor and ensure that the following two properties are set to true.

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   <GeneratePkgDefFile>true</GeneratePkgDefFile>
   <CopyBuildOutputToOutputDirectory>true</CopyBuildOutputToOutputDirectory>

2. The second step to configuring the extension is updating your source.extension.vsixmanifest file to include a line to inform Visual Studio that your extension includes a pkgdef file. If you are using version 1 of this file (i.e. the file starts with <Vsix Version="1.0.0"), make sure the following line is included inside the <Content> element.

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   <VsPackage>|%CurrentProject%|</VsPackage>

   If your extension uses version 2 of this file, [TODO: fill this in].

Visual Studio 2012 and Newer

[assembly: ProvideCodeBase(
    AssemblyName = "{AssemblyName}",
    Version = "{AssemblyVersion}",
    CodeBase = "$PackageFolder$\\{AssemblyFile}")]

Visual Studio 2010 and Newer

using System;
using System.Reflection;
using System.Runtime.InteropServices;
using Microsoft.VisualStudio.Shell;

[AttributeUsage(AttributeTargets.Assembly, AllowMultiple = false)]
internal sealed class ProvideBindingPathAttribute : RegistrationAttribute
{
    private static string GetPathToKey(RegistrationContext context)
    {
        Guid componentGuid = GetAssemblyGuid(context.CodeBase);
        return string.Concat(@"BindingPaths\", componentGuid.ToString("B").ToUpperInvariant());
    }

    private static Guid GetAssemblyGuid(string codeBase)
    {
        string assemblyFile = new Uri(codeBase).LocalPath;
        Assembly assembly = Assembly.LoadFrom(codeBase);
        object[] attributesData = assembly.GetCustomAttributes(typeof(GuidAttribute), false);
        if (attributesData.Length == 0)
            throw new ArgumentException("The specified assembly did not contain a [Guid] attribute.");

        return new Guid(((GuidAttribute)attributesData[0]).Value);
    }

    public override void Register(RegistrationContext context)
    {
        if (context == null)
            throw new ArgumentNullException("context");

        using (Key childKey = context.CreateKey(GetPathToKey(context)))
        {
            childKey.SetValue(context.ComponentPath, string.Empty);
        }
    }

    public override void Unregister(RegistrationContext context)
    {
        if (context == null)
            throw new ArgumentNullException("context");

        context.RemoveKey(GetPathToKey(context));
    }
}

[assembly: ProvideBindingPath]