「Let's Play TDD #3: Cleaning Up My Mess」の写経 http://www.takaiwa.net/2014/01/lets-play-tdd-3-cleaning-up-my-mess.html

SavingAccountYear.java

package com.jamesshore.finances;
/**
 * <p>
 * Let's Play TDD #3: Cleaning Up My Mess
 * https://www.youtube.com/watch?v=jnMMkXzpOS4
 * </p>
 * Current Source code:
 * https://www.youtube.com/watch?v=jnMMkXzpOS4&t=870
 *
 * @author takaiwa.net
 */
public class SavingAccountYear {

    private int startingBalance = 0;
    private int interestRate = 0;

    public SavingAccountYear(){}

    public SavingAccountYear(int startingBalance, int interestRate) {
        this.startingBalance = startingBalance;
        this.interestRate = interestRate;
    }

    public int startingBalance() {
        return startingBalance;
    }

    public void deposit(int amount) {
        startingBalance += amount;
    }

    public int balance() {
        return startingBalance;
    }

    public void withdraw(int amount) {
        startingBalance -= amount;
    }

    public SavingAccountYear nextYear() {
        return  new SavingAccountYear(this.endingBalance(), interestRate);
    }

    public int endingBalance() {
        return balance() + (balance() * interestRate / 100);
    }

    public int interestRate() {
        return interestRate;
    }
}