public async Task Handle_ConferenceAlreadyOpen_NoExceptionAndDontPublishNotification()
        {
            const string conferenceId = "test";

            // arrange
            SetConferenceIsOpen(conferenceId);
            InitializeConferenceInRepository(conferenceId);

            var handler = CreateHandler();

            // act
            await handler.Handle(new OpenConferenceRequest(conferenceId), CancellationToken.None);

            // assert
            ConferenceManagementHelper.VerifyAnyFindConferenceById(_mediator);
            _mediator.VerifyNoOtherCalls();
        }
        public async Task Handle_ConferenceDoesNotExist_ThrowConferenceNotFoundException()
        {
            const string conferenceId = "test";

            // arrange
            SetConferenceIsClosed(conferenceId);
            var handler = CreateHandler();

            ConferenceManagementHelper.SetConferenceDoesNotExist(_mediator, conferenceId);

            // act & assert
            await Assert.ThrowsAsync <ConferenceNotFoundException>(async() =>
            {
                await handler.Handle(new OpenConferenceRequest(conferenceId), CancellationToken.None);
            });

            ConferenceManagementHelper.VerifyAnyFindConferenceById(_mediator);
            _mediator.VerifyNoOtherCalls();
            _openConferenceRepository.VerifyNoOtherCalls();
        }