Tests.ClientTests.A_new_client_can_be_registered_Observer C# (CSharp) Method

        public void A_new_client_can_be_registered_Observer()
        {
            // here we use the observer pattern to register an action (the subscriber) to
            // handle an event of type ClientRegistered which will be raised by the entity (the publisher)
            var eventHelper = new EventHandlerStub();
            DomainEvent.Current.Subscribe<ClientRegistered>(eventHelper.Handle);

            var idNumber = new IdentityNumber("5008035176089");
            var telephoneNumber = new TelephoneNumber("0125552222");
            var clientName = new PersonName("Adrian", "Freemantle");
            new Client(idNumber, clientName, telephoneNumber);

            eventHelper.RaisedEvents.Count.ShouldBe(1);
            eventHelper.RaisedEvents.First().ShouldBeTypeOf<ClientRegistered>();
            ((ClientRegistered)eventHelper.RaisedEvents.First()).ClientId.ShouldBe(idNumber.Number);
            ((ClientRegistered)eventHelper.RaisedEvents.First()).FirstName.ShouldBe(clientName.FirstName);
            ((ClientRegistered)eventHelper.RaisedEvents.First()).Surname.ShouldBe(clientName.Surname);
            ((ClientRegistered)eventHelper.RaisedEvents.First()).TelephoneNumber.ShouldBe(telephoneNumber.Number);
        }