public async Task TestGetServiceSI_GetsServiceOfTypeIRegisteredByS()
        {
            Mock <IVsSolution> solutionMock = ServiceProviderMock.SetupService <SVsSolution, IVsSolution>();

            await RunPackageInitializeAsync();

            _objectUnderTest.AddService(
                typeof(SVsSolution),
                (container, token, type) => Task.FromResult <object>(solutionMock.Object));

            IVsSolution service = _objectUnderTest.GetService <SVsSolution, IVsSolution>();

            Assert.AreEqual(solutionMock.Object, service);
        }