How to mock events with internal constructors

I have a service responsible for subscribing to EWS for new mail notification. I've created an interface for the service in order to mock it and test a dummy implementation. However, I'm running into a wall whenever I try to manually tell what my events are supposed to do.

Here is my concrete implementation.

public interface IExchangeService
{
    void Subscribe();
}

public class ExchangeServiceSubscriber : IExchangeService
{
    private readonly ExchangeService _exchangeService;
    private readonly IConsumer<IEmail> _consumer;

    public ExchangeServiceSubscriber(
        ExchangeService exchangeService, 
        IConsumer<IEmail> consumer)
    {
        _exchangeService = exchangeService;
        _consumer = consumer;
    }

    public void Subscribe()
    {
        // code to subscribe

        streamingConnection.OnNotificationEvent += OnEvent;

        streamingConnection.Open();
    }

    public void OnEvent(object sender, NotificationEventArgs args)
    {
        foreach (NotificationEvent triggeredEvent in args.Events)
        {
            if (triggeredEvent is ItemEvent)
            {
                var propertySet = new PropertySet(ItemSchema.UniqueBody, ItemSchema.Attachments)
                {
                    RequestedBodyType = BodyType.Text
                };
                EmailMessage email = EmailMessage.Bind(args.Subscription.Service,
                                                       ((ItemEvent)triggeredEvent).ItemId, propertySet);

                _consumer.Consume(new ExchangeEmail { Body = email.UniqueBody });
            }
        }
    }
}

And unfortunatly, almost every class in EWS is either sealed or has an internal constructor which really limits how I decouple them, it seems. I've attempted to set the expectation for NotificationEventArgs (for example) but it uses an internal constructor.

Here is some ideas I've been fiddling with. You can read about mocking events here.

mock.Setup(x => x.OnEvent(new object(), new NotificationEventArgs())); Issue with that is NotificationEventArgs uses an internal constructor.

I could see getting this working with some sort of wrapper but I'm not exactly sure what it would look like. One of the big problems is the way EWS is made pretty much prevents anyone from manua开发者_C百科lly injecting dependencies. I'm essentially trying to test that whenever event OnEvent fires that the email will actually get consumed. Also, while I would like to test this functionality I'm not sure it's worth fighting EWS every step of the way.

Let's first see, what you can't do:

• You can't subclass NotificationEventArgs because the ctor is internal.
• You can't create an instance directly for the same reason.

So basically, you can't create an instance of this class using the "normal way". I assume you already checked for a factory method or class?

This leaves us with only one option: Instantiate the class using reflection, e.g. with the help of the Activator.CreateInstance method: Unit testing exception handling for third party exceptions with internal constructors, like so:

mock.Setup(x => x.OnEvent(new object(), 
           Activator.CreateInstance(typeof(NotificationEventArgs),
                               BindingFlags.NonPublic | BindingFlags.Instance,
                               null,
                               null,
                               null))
           );