public void ExchangeFromUsdToEur()
        {
            string USD = "USD";
            string EUR = "EUR";
            float ammount = 2.45F;

            CurrencyExchanger ce = new CurrencyExchanger();

            Assert.AreEqual(ce.ExchangeValue(USD, EUR, ammount), (ce.GetRate(USD) / ce.GetRate(EUR)) * ammount);
        }
        public void GetInvalidCurrencyRate()
        {
            string NonValidCurrency = "ABC";
            float result;
            Exception ex = null;

            CurrencyExchanger ce = new CurrencyExchanger();

            try
            {
                result = ce.GetRate(NonValidCurrency);
            }
            catch (Exception e)
            {
                ex = e;
            }

            Assert.IsInstanceOfType(ex, typeof(CurrencyNotFoundException));
        }