public void CreateUser_Call_Create_User_If_Validation_Checks_Where_Successful()
        {
            var user = new User();

            GivenAllValidationCheckAreSuccessful();

            var result = _sut.CreateUser(user);

            Received.InOrder(() =>
            {
                _credentialService.UserExists(Arg.Any <User>());
                _credentialService.CheckUserCredentials(Arg.Any <User>());
                _userRepository.CreateUser(Arg.Any <User>());
            });

            result.ShouldBeOfType <ApiResult>();
            result.Success.ShouldBeTrue();
        }