public void TestReduceSum()
{
Expression sum = new Sum(Money.Dollar(3), Money.Dollar(4));
Bank bank = new Bank();
Money actual = bank.Reduce(sum, "USD");
Assert.Equal(Money.Dollar(7), actual);
}
public void TestSumTimes()
{
Expression fiveBucks = Money.Dollar(5);
Expression tenFrancs = Money.Franc(10);
Bank bank = new Bank();
bank.AddRate("CHF", "USD", 2);
Expression sum = new Sum(fiveBucks, tenFrancs).Times(2);
Money actual = bank.Reduce(sum, "USD");
Assert.Equal(Money.Dollar(20), actual);
}