测试事件聚合器的订阅

多亏了

这个答案，我设法测试了PRISM EventAggregator的发布事件（用FakeItEasy伪造）

[TestCase]
public void test_that_publish_occured()
{
    var fakeEventAg = A.Fake<IEventAggregator>();
    var fakeEvent = A.Fake<MyEvent>();
    A.CallTo(() => fakeEventAg.GetEvent<MyEvent>())
      .Returns(fakeEvent);
    MyViewModel mvm = new MyViewModel(fakeEventAg);
    mvm.ICommandThatCausesPublishToBeCalled.Execute();
    A.CallTo(() => fakeEvent.Publish(A<SomeClass>.Ignored))
      .MustHaveHappened();
}

但是我未能测试订阅此事件。我尝试了以下方法，但出现异常"无法拦截非虚拟方法"。

[TestCase]
public void test_that_event_is_listened()
{
    var fakeEventAg = A.Fake<IEventAggregator>();
    var fakeEvent = A.Fake<MyEvent>();
    A.CallTo(() => fakeEventAg.GetEvent<MyEvent>())
      .Returns(fakeEvent);
    // subscription occurs in the constructor
    MyViewModel2 mvm2 = new MyViewModel2(fakeEventAg);
    A.CallTo(() => fakeEventAg.GetEvent<MyEvent>()
      .Subscribe(A<Action<PayloadClass>>.Ignored))
      .MustHaveHappened();
}

如何测试事件是否已订阅？它不一定是单元测试，但也可以是集成测试。