public void ClearTest()
{
var listener = new GenericHandler <object>();
IEventAggregator eventAggregator = CreateEventAggregator();
eventAggregator.Subscribe(listener);
eventAggregator.GetObservers().Contains(listener).ShouldBeTrue();
eventAggregator.GetObservers().Count.ShouldEqual(1);
eventAggregator.Clear();
eventAggregator.GetObservers().Count.ShouldEqual(0);
}