public void BeforeEachTest()
 {
     inputModel = new ReferFriendInputModel
     {
         UserEmail = "*****@*****.**",
         Friend1Email = "*****@*****.**",
         Friend2Email = "*****@*****.**",
         Friend3Email = "*****@*****.**",
         Friend4Email = "*****@*****.**",
         Friend5Email = "*****@*****.**"
     };
 }
        public PartialViewResult Index(ReferFriendInputModel inputModel)
        {
            if (ModelState.IsValid && ValidateExisting(inputModel.GetFriends()))
            {
                var friendUsers = inputModel.GetFriends().Select(u => new Customer { Email = u } ).ToList();
                customerService.Referral(new Customer { Email = inputModel.UserEmail.ToLower() }, friendUsers);

                return PartialView("SendPromoCode");
            }

            var viewModel = new ReferFriendViewModel
            {
                UserEmail = ToNullSafeLower(inputModel.UserEmail),
                Friend1Email = ToNullSafeLower(inputModel.Friend1Email),
                Friend2Email = ToNullSafeLower(inputModel.Friend2Email),
                Friend3Email = ToNullSafeLower(inputModel.Friend3Email),
                Friend4Email = ToNullSafeLower(inputModel.Friend4Email),
                Friend5Email = ToNullSafeLower(inputModel.Friend5Email)
            };

            return PartialView("Index", viewModel);
        }