public void Rhino_onSpecificDrugsRetrieved_WhenEventRaised_DrugServiceListens() { // Arrange var mockDrugService = MockRepository.GenerateMock <IDrugService>(); _dataAccess.SpecificDrugRetrievedEvent += mockDrugService.OnSpecificDrugsRetrieved; // Act _dataAccess.GetSpecificDrugs(_drugIds); // Assert mockDrugService.AssertWasCalled(ds => ds.OnSpecificDrugsRetrieved(Arg <object> .Is.Equal(_dataAccess), Arg <SpecificDrugRetrievedArgs> .Matches(a => Equals(a.DrugIds, _drugIds)))); }