public async Task ThenAnInvitationIsAdded( [Frozen] Mock <IAuthenticationService> authService, [Frozen] Mock <IMediator> mediator, RegistrationController controller) { //arrange mediator.Setup(x => x.Send(It.Is <GetInvitationQuery>(s => s.Ukprn == authService.Object.Ukprn), It.IsAny <CancellationToken>())).ReturnsAsync(new GetInvitationQueryResult(new List <InvitationDto>())); //act await controller.InvitedEmployers(null, null); //assert mediator.Verify(x => x.Send(It.IsAny <GetInvitationQuery>(), It.IsAny <CancellationToken>()), Times.Once); }