Junit/Mockito - 等待方法执行

Question

在我的应用程序中，我使用observer模式进行某些操作，我想在单元测试中对它们进行测试。问题是我不知道如何使用junit/mockito /别的东西来测试观察者。任何帮助？

例如，这是我的单元测试：

@Before 
public void setUp() throws IOException, Exception { 
    observer = new GameInstanceObserver(); // observable (GameInstance) will call update() method after every change 
    GameInstance.getInstance().addObserver(observer); // this is observable which is updated by serverService 
} 

@Test(expected = UserDataDoesntExistException.class) 
public void getRoomUserData_usingNullKey_shouldThrowUserDataDoesntExist() throws InterruptedException, UserDataDoesntExistException { 
    serverService.createRoom("exampleRoom"); // this operation is asynchronous and updates GameInstance data (as I wrote before GameInstance is Observable) 
    Thread.sleep(400); // how to do it in better way? 

    GameInstance gi = (GameInstance) observer.getObservable(); 
    assertTrue(gi.getRoom("exampleRoom").getRoomId().equals("exampleRoom")); 
} 

我想不使用Thread.sleep()并以这种方式使用它（或类似）：

@Test(expected = UserDataDoesntExistException.class) 
public void getRoomUserData_usingNullKey_shouldThrowUserDataDoesntExist() throws InterruptedException, UserDataDoesntExistException { 
    serverService.createRoom("exampleRoom"); // this operation is asynchronous and updates GameInstance data (as I wrote before GameInstance is Observable) 
    waitUntilDataChange(GameInstance.getInstance()); // wait until observable will be changed so I know that it notified all observer and I can validate data 

    GameInstance gi = (GameInstance) observer.getObservable(); 
    assertTrue(gi.getRoom("exampleRoom").getRoomId().equals("exampleRoom")); 
} 

Answer 1

如果我理解正确的话，问题不是真的要测试观察者，而是测试异步方法调用的结果。要做到这一点，创建一个阻止其update（）方法被调用的观察者。像下面这样：

public class BlockingGameObserver extends GameInstanceObserver { 
    private CountDownLatch latch = new CountDownLatch(1); 

    @Override 
    public void update() { 
     latch.countDown(); 
    } 

    public void waitUntilUpdateIsCalled() throws InterruptedException { 
     latch.await(); 
    } 
} 

并在测试：

private BlockingGameObserver observer; 

@Before 
public void setUp() throws IOException, Exception { 
    observer = new BlockingGameObserver(); 
    GameInstance.getInstance().addObserver(observer); 
} 

@Test 
public void getRoomUserData_usingNullKey_shouldThrowUserDataDoesntExist() throws InterruptedException, UserDataDoesntExistException { 
    serverService.createRoom("exampleRoom"); 
    observer.waitUntilUpdateIsCalled(); 
    assertEquals("exampleRoom", 
       GameInstance.getInstance().getRoom("exampleRoom").getRoomId()); 
}