在Android代码中模拟AsyncTasks和Intents创建的优雅方法

Question

我有一个Android活动,其中有一些调用

final ConnectToServerAsyncTask task = new ConnectToServerAsyncTask(...);

和

final Intent intent = new Intent(this, SomeActivity.class);

为了单元测试这个类,我需要能够嘲笑的创建ConnectToServerAsyncTask和Intent(例如使用的Mockito).

有比下面描述的方法更优雅的方法吗？

public class MainActivityOfTheApp extends Activity {
    private IAsyncTaskFactory asyncTaskFactory = new AsyncTaskFactory();
    private IIntentFactory intentFactory = new IntentFactory();

    public void setAsyncTaskFactory(final IAsyncTaskFactory aFactory)
    {
        asyncTaskFactory = aFactory;
    }

    public void setIntentFactory(final IIntentFactory aFactory)
    {
        intentFactory = aFactory;
    }

    @Override
    protected void onResume() {
        ...
        final ConnectToServerAsyncTask task = asyncTaskFactory.create(...);
        ...

        final Intent intent = intentFactory.create(this, OtherActivity.class);
        ...
    }
}

在单元测试中,我将创建一个MainActivityOfTheApp实例,然后使用setAsyncTaskFactory和注入模拟setIntentFactory.

Answer 1

PowerMock

您可以使用PowerMock模拟构造函数.

所以在你的情况下,测试看起来像这样:

@RunWith(PowerMockRunner.class)
@PrepareForTest(MainActivityOfTheApp.class)
public class MainActivityOfTheAppTest{
  private AsyncTaskFactory asyncTaskFactory;
  private IntentFactory intentFactory;
  private MainActivityOfTheApp mainActivityOfTheApp;

  @Before
  public void prepare() {
    asyncTaskFactory = PowerMockito.mock(AsyncTaskFactory.class);
    intentFactory = PowerMockito.mock(IntentFactory.class);
    PowerMockito.whenNew(AsyncTaskFactory.class).withNoArguments().thenReturn(asyncTaskFactory);
    PowerMockito.whenNew(IntentFactory.class).withNoArguments().thenReturn(intentFactory);
    mainActivityOfTheApp = new MainActivityOfTheApp();
  }

  @Test
  public void doTest() {
    //mainActivityOfTheApp has the mocks in final field inside, no need for the setters.
  }
}

我必须指出,PowerMock功能强大,但经常遇到复杂的类加载(例如OSGI环境)或代码覆盖工具(例如jacoco)的问题.它通常有效,但我浪费了一些时间.

没有PowerMock

第二种可能性是创建包私有(无修饰符.为什么不保护或公共？看看构造函数中的可覆盖方法调用有什么问题？)方法,它们调用构造函数如下:

public class MainActivityOfTheApp extends Activity {
    private final IAsyncTaskFactory asyncTaskFactory = constructAsyncTaskFactory();
    private final IIntentFactory intentFactory = constructIntentFactory();

    IAsyncTaskFactory constructAsyncTaskFactory()
    {
        return new AsyncTaskFactory();
    }

    IIntentFactory constructIntentFactory()
    {
        return new IntentFactory();
    }
    ...
}

然后在你的单元测试中(测试必须与测试类在同一个包中!)你重写构造*()方法:

public class MainActivityOfTheAppTest{
  private AsyncTaskFactory asyncTaskFactory;
  private IntentFactory intentFactory;
  private MainActivityOfTheApp mainActivityOfTheApp;

  @Before
  public void prepare() {
    asyncTaskFactory = mock(AsyncTaskFactory.class);
    intentFactory = mock(IntentFactory.class);
    mainActivityOfTheApp = new HackedMainActivityOfTheApp();
  }

  @Test
  public void doTest() {
    //mainActivityOfTheApp has the mocks in final field inside, no need for the setters.
  }

  private class HackedMainActivityOfTheApp extends MainActivityOfTheApp {
        IAsyncTaskFactory constructAsyncTaskFactory()
        {
            return asyncTaskFactory;
        }

        IIntentFactory constructIntentFactory()
        {
            return intentFactory;
        }
  }
}

如果您对包含MainActivityOfTheApp的jar进行签名,则可以保护construct*方法.请参阅/sf/answers/67802871/:

此外,补丁更难(你必须重新签署jar),类补丁是不可能的(单个包中的所有类必须具有相同的签名源)并且拆分罐变成一件苦差事.