public void CanGetTotalOfAccountBalances()
        {
            DataHelper.NewDb();

            var service = new RentalsService();
            var total   = 0.00m;

            foreach (var account in DataHelper.Accounts)
            {
                total += DataHelper.GetAccountBalance(account.Id);
            }

            Assert.AreEqual(total, service.GetTotalOfAccountBalances());
        }