public void CalculateOER()
        {
            IAccountingCalculator calc = new AccountingCalculator();
            decimal net = calc.CalculateOER(1000m, 500m);

            Assert.AreEqual(0.5m, net);
        }
        protected void btnDisplayTotals_Click(object sender, EventArgs e)
        {
            try
            {
                decimal revenue  = decimal.Parse(txtRevenue.Text);
                decimal expenses = decimal.Parse(txtExpenses.Text);

                IAccountingCalculator calculator = new AccountingCalculator();
                decimal net = calculator.CalculateNet(revenue, expenses);

                litNet.Text = net.ToString("C");

                decimal oer = calculator.CalculateOER(revenue, expenses);
                litOer.Text = oer.ToString("P2");

                var maxOer = Convert.ToDecimal(ConfigurationManager.AppSettings["MaxAcceptableOER"]);

                if (oer > maxOer)
                {
                    litOer.CssClass = "badOer";
                }
                else
                {
                    litOer.CssClass = "goodOer";
                }

                pnlError.Visible = false;
            }
            catch
            {
                pnlError.Visible = true;
            }
        }
 public void ZeroRevenueWhenCalculatingOER()
 {
     IAccountingCalculator calc = new AccountingCalculator();
     decimal net = calc.CalculateOER(0m, 1000m);
 }