public async Task Should_return_participant_not_found_when_request_is_sent() { _videoApiClientMock .Setup(x => x.LeavePrivateConsultationAsync(It.IsAny <LeaveConsultationRequest>())) .Returns(Task.FromResult(default(object))); var conference = new Conference { Id = Guid.NewGuid() }; _conferenceCacheMock.Setup(cache => cache.GetOrAddConferenceAsync(conference.Id, It.IsAny <Func <Task <ConferenceDetailsResponse> > >())) .Callback(async(Guid anyGuid, Func <Task <ConferenceDetailsResponse> > factory) => await factory()) .ReturnsAsync(conference); var leaveConsultationRequest = Builder <LeavePrivateConsultationRequest> .CreateNew() .With(x => x.ConferenceId = conference.Id).Build(); var result = await _controller.LeavePrivateConsultationAsync(leaveConsultationRequest); var typedResult = (NotFoundResult)result; typedResult.Should().NotBeNull(); }