EasyMock简介和代码示例 - 开源资源分享

关于EasyMock：

注意：

3.0版本前，使用JDK的动态代理实现Mock对象创建，因此只能对接口进行mock，如果需要对类进行mock，需要使用扩展org.easymock.classextension.EasyMock
3.0后，可以针对接口&类进行mock

EasyMock范例（Service层代码单元测试）：

1.工程中引入EasyMock包：

maven工程的话，pom包中添加依赖：

<dependency>
    <groupId>org.easymock</groupId>
    <artifactId>easymock</artifactId>
    <version>3.4</version>
    <scope>test</scope>
</dependency>

2.被测对象：

public class UserService{
    @Resource
    private UserDao userDao;
    
    private String getUserName(String userId)
    {
        User user = userDao.select(userId);
        
        if (null == user)
        {
            return "";
        }else {
            return "offline_" + user.getName();
        }
    }
}

其中UserService依赖UserDao接口的实现

3.测试代码

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:CommonUtils.xml")
public class UserServiceTest{

    private UserDao userDaoMock = null;
    
    private User userMock = null;

    @Resource
    private UserService userService;
    
    @Before
    public void setUp()
    {
        // 创建mock对象
        userDaoMock = EasyMock.createMock(UserDao.class);
        userMock = EasyMock.createMock(User.class);
        
        // mock对象注入被测对象
        Field userDaoField = userService.getDeclaredField("userDao");
        userDaoField.setAccessible(true);
        userDaoField.set(userService,userDaoMock);
    }
    
    @Test
    public void getUserName()
    {
        // 设置mock对象的期望值
        EasyMock.expect(userMock.getName()).andReturn("testName");
        EasyMock.expect(userDaoMock.select("1")).andReturn(userMock);
        
        // mock对象的replay
        EasyMock.replay(userMock);
        EasyMock.replay(userDaoMock);
        
        // 断言
        Assert.assertTrue(userService.getUserName("1")
        			.equals("offline_testName"));
        
        // 验证mock对象是否被调用
        EasyMock.verify(userMock);
        EasyMock.verify(userDaoMock);
    }
    
    @After
    public void tearDown() throws Exception {
        userDaoMock = null;
        userMock = null;
    }
}

根据官方文档，mock的todolist有：

Create the mock
Have it set to the tested class
Record what we expect the mock to do
Tell all mocks we are now doing the actual testing
Test
Make sure everything that was supposed to be called was called

我们范例中对应是：

1.使用EasyMock生成Mock对象：

userDaoMock = EasyMock.createMock(UserDao.class);
userMock = EasyMock.createMock(User.class);

2.Mock对象注入被测对象：

Field userDaoField = userService.getDeclaredField("userDao");
userDaoField.setAccessible(true);
userDaoField.set(userService,userDaoMock);

3.设定Mock对象的预期行为和输出：

EasyMock.expect(userMock.getName()).andReturn("testName");
EasyMock.expect(userDaoMock.select("1")).andReturn(userMock);

4.将Mock对象切换到Replay状态：

EasyMock.replay(userMock);
EasyMock.replay(userDaoMock);

5.调用Mock对象方法进行单元测试：

Assert.assertTrue(userService.getUserName("1").equals("offline_testName"));

6.确定mock对象有被调用：

EasyMock.verify(userMock);
EasyMock.verify(userDaoMock);

EasyMock进阶：

使用IMocksControl管理多个mock对象

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:CommonUtils.xml")
public class UserServiceTest{

    private IMocksControl iMocksControl = null;

    private UserDao userDaoMock = null;
    
    private User userMock = null;

    @Resource
    private UserService userService;
    
    @Before
    public void setUp()
    {
        // 创建mock对象
        iMocksControl = EasyMock.createControl();
        userDaoMock = iMocksControl.createMock(UserDao.class);
        userMock = iMocksControl.createMock(User.class);
        
        // mock对象注入被测对象
        Field userDaoField = userService.getDeclaredField("userDao");
        userDaoField.setAccessible(true);
        userDaoField.set(userService,userDaoMock);
    }
    
    
    @Test
    public void getUserName()
    {
        // 设置mock对象的期望值
        EasyMock.expect(userMock.getName()).andReturn("testName");
        EasyMock.expect(userDaoMock.select("1")).andReturn(userMock);
        
        // mock对象的replay
        iMocksControl.replay();
        
        // 断言
        Assert.assertTrue(userService.getUserName("1").equals("offline_testName"));
        
        // 验证mock对象是否被调用
        iMocksControl.verify();
    }
    
    @After
    public void tearDown() throws Exception {
        userDaoMock = null;
        userMock = null;
    }
}

使用注解

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:CommonUtils.xml")
public class UserServiceTest{
    @Rule
    private EasyMockRule mocks = new EasyMockRule(this);
    private IMocksControl iMocksControl = null;
    @Mock
    private UserDao userDaoMock = null;
    private User userMock = null;
    @TestSubject
    @Resource
    private UserService userService;
    ...
}

解析：

1.mock对象会被注入到userService对象中，@Mock是需要创建的mock对象，@TestSubject是被测类
2.如果没有下面这段代码设置Junit的rule，需要将测试类的Runner设置为@RunWith(EasyMockRunner.class)，当你希望使用别的runner类，但是又需要EasyMock的注解时，使用Junit的rule进行扩展

@Rule
private EasyMockRule mocks = new EasyMockRule(this);

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