easymock是众多mock之中的很容易用的mock,今天刚开始学习,来个简单的教程.以购物车结算为例子,比如首先是每一个商品项的pojo

[code="java"]

public class Item {

private String name;
private int quantity;

public Item(String name, int quantity) {
super();
this.name = name;
this.quantity = quantity;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getQuantity() {
return quantity;
}
public void setQuantity(int quantity) {
this.quantity = quantity;
}
[/code]

然后是购物车的:
[code="java"]
public class ShoppingCart {

private String name;
private Store store = null;

private List<Item> items = new ArrayList();

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public List<Item> getItems() {
return items;
}

public void setItems(List<Item> items) {
this.items = items;
}

public void addItem(Item item)
{
items.add(item);
}

public void setStore(Store store)
{
this.store=store;
}

public Store getStore()
{
return (this.store);
}

public Double calculateTotal()
{
Double total = 0.0;
for (Item item : this.items) {
total+= (store.getPrice(item.getName()) * item.getQuantity());
}
 
DecimalFormat decim = new DecimalFormat("0.00");
Double price = Double.parseDouble(decim.format(total));
   
return price;
}
[/code]

在这个购物车的计算中,在计算总价格方面,
 total+= (store.getPrice(item.getName()) * item.getQuantity());
  这里,依赖了一个额外的对象store,根据store.getPrice()方法求出某个商品的单价,
但这里模拟的是现在根本不知道这个store 是如何实现的,有可能是第三方的,于是
easymock就派上用长了,它可以根据接口去模拟一个实现出来,下面直接看
ShoppingCartTest .java

[code="java"]
public ShoppingCart cart = null;
public Store storeMock = null;

@Before
public void initialize()
{
cart = new ShoppingCart();
storeMock = EasyMock.createMock(Store.class);
cart.setStore(storeMock);
}

@Test     
    public void testShoppingCart()
{

EasyMock.expect(storeMock.getPrice("Mead Spiral Bound Notebook, College Rule")).andReturn(5.99);
EasyMock.expect(storeMock.getPrice("Kindle Fire HD 8.9")).andReturn(499.99);

//开始使用mock
EasyMock.replay(storeMock);

Item item1 = new Item("Mead Spiral Bound Notebook, College Rule", 3);
Item item2 = new Item("Kindle Fire HD 8.9",1);

cart.addItem(item1);
cart.addItem(item2);

double total = cart.calculateTotal();

System.out.println("Total price of items in shopping cart: $"+total);
assertEquals("Result",505.96, total,0);
}

@After
public void cleanup() 
{
cart=null;
storeMock=null;
}
    
[/code]
   同junit一样,在before中,
@Before
public void initialize()
{
cart = new ShoppingCart();
storeMock = EasyMock.createMock(Store.class);
cart.setStore(storeMock);
}
   
storeMock = EasyMock.createMock(Store.class);就可以模拟一个实现出来了,
  然后
EasyMock.expect(storeMock.getPrice("Mead Spiral Bound Notebook, College Rule")).andReturn(5.99);
 这里,使用easymock的断言机制,断言出这个属的单价是5.99,然后记得使用
EasyMock.replay(storeMock);就可以在真正的测试中,使用store这个对象了;最后记得cleanup中清理下.
     简单来说,mock系列框架的大概原理就这样了,接下来就是深入的学习