public void TestPlusReturnsSum()
{
Money five = Money.Dollar(5);
MoneyExpression result = five.Plus(five);
Sum sum = (Sum)result;
Assert.Equal(five, sum.augend);
Assert.Equal(five, sum.addend);
}
public void TestSimpleAddition()
{
Money five = Money.Dollar(5);
MoneyExpression sum = five.Plus(five);
Bank bank = new Bank();
Money reduced = bank.Reduce(sum, "USD");
Assert.Equal(Money.Dollar(10), reduced);
}
public void TestMixedAddition()
{
MoneyExpression fiveBucks = Money.Dollar(5);
MoneyExpression tenFrancs = Money.Franc(10);
Bank bank = new Bank();
bank.AddRate("CHF", "USD", 2);
Money result = bank.Reduce(fiveBucks.Plus(tenFrancs), "USD");
Assert.Equal(Money.Dollar(10), result);
}
public void TestSumTimes()
{
MoneyExpression fiveBucks = Money.Dollar(5);
MoneyExpression tenFrancs = Money.Franc(10);
Bank bank = new Bank();
bank.AddRate("CHF", "USD", 2);
MoneyExpression sum = new Sum(fiveBucks, tenFrancs).Times(2);
Money result = bank.Reduce(sum, "USD");
Assert.Equal(Money.Dollar(20), result);
}
public MoneyExpression Plus(MoneyExpression addend)
{
return(new Sum(this, addend));
}
public Money Reduce(MoneyExpression source, string to)
{
return(source.Reduce(this, to));
}
public Sum(MoneyExpression augend, MoneyExpression addend)
{
this.augend = augend;
this.addend = addend;
}