Prism TDD Unsubscribe()

我正在使用TDD，并希望为PubSubEvent中可用的Unsubscribe()方法编写一个单元测试。因为没有接口作为你从父类继承的，父类没有接口，所以我不知道如何测试它。

我的服务和方法，我想测试一下:

public class FrameService: IFrameService
{
     private readonly IEventAggregator _eventAggregator;
     public void UnsubscribeEvents()
     {
         _eventAgregator.GetEvent<FrameAddedEvent>()
                        .Unsubscribe(FrameAddedEventHandler); // How to unit test this?
      }
 }

FrameAddedEvent类，继承自Prism库中的PubSubEvent:

public class FrameAddedEvent: PubSubEvent<Frame>
{
}

在Prism库中的声明:

public class PubSubEvent<TPayload> : EventBase
{  
    public SubscriptionToken Subscribe(Action<TPayload> action);
}

我对代码行的第一部分的测试(使用MSTest和Moq)。现在我需要另一个UnitTest，在Unsubscribe()

上断言

[TestClass]
public class FrameServiceTest
{
    private Mock<IEventAgregator> _eventAgregator;
    [TestMethod]
    public void When_SubscribeEvents_Then_Get_FrameAddedEvent_From_EventAggregator()
    {
        var frameAddedEvent = new FrameAddedEvent();
        _eventAgregator.Setup(x=>x.GetEvent<FrameAddedEvent>())
                                   .Returns(frameAddedEvent);
        _frameService.SubscribeEvents();
        _serviceLayerEventAgregator.Verify(x => x.GetEvent<FrameAddedEvent>(), Times.Once);
    }
}

答:请看下面的解释，我只是为那些可能和我有同样问题的人添加了代码。

伪类:

public class FakeFrameAddedEvent : FrameAddedEvent
{
    public bool Unsubscribed { get; private set; }
    public FakeFrameAddedEvent()
    {
        Unsubscribed = false;
    }
    public override void Unsubscribe(Action<Frame> subscriber)
    {
        Unsubscribed = true;
    }
}

和新的UnitTest:

    [TestMethod]
    public void When_UnsubscribeEvents_Then_Unsubscribe_Is_Call()
    {
        var frameAddedEvent = new FakeFrameAddedEvent();
        _serviceLayerEventAgregator.Setup(x => x.GetEvent<FrameAddedEvent>())
                                   .Returns(frameAddedEvent);
        _frameService.UnsubscribeEvents();
        Check.That(frameAddedEvent.Unsubscribed).IsTrue();
    }