public void OffersOwnServices()
    {
        var childServiceProvider = new ChildServiceProvider(this.parentServiceProvider);

        childServiceProvider.AddService(typeof(IVsProject), new Mock <IVsProject>().Object);
        Assert.NotNull(childServiceProvider.GetService(typeof(IVsProject)));
    }
    public void OffersParentServices()
    {
        var childServiceProvider = new ChildServiceProvider(this.parentServiceProvider);

        Assert.IsAssignableFrom <IVsSolution>(childServiceProvider.GetService(typeof(SVsSolution)));
    }