Cannot use Mock<T>.Raise() on WPF Routed Events

[perlun]

Hi,

Trying to unit test some WPF-related code and in that situation, I'm trying to get the code below to work:

var listView = new Mock<ListView>();
listView.Raise(lv => lv.Unloaded += null, EventArgs.Empty);

However, this gives me an ArgumentNullException with the following message:

Value cannot be null.Parameter name: handler 

Skipping the EventArgs.Empty makes no difference.

If I change my example to something like this:

void Main()
{
    var listView = new Mock<ListView>();
    listView.Raise(lv => lv.Unloaded += Foo);   
}

void Foo(object sender, RoutedEventArgs e)
{
}

...I get a different exception (ArgumentException).

Expression is not an event attach or detach, or the event is declared in a
class but not marked virtual

So, is the conclusion basically that we cannot mock these events, since they aren't virtual? That's what the exception message is telling me, but I just want to check... Are there any other realistic test scenarios for 3rd party classes which uses events?

[kzu]

Events are no different than everything else. They have to be virtual to be mockable.