android - ActivityInstrumentationTestCase2 getActivity() 永不返回

Question

每当我在我的 Android 测试项目中运行所有测试时，我的一个测试永远不会完成。使用 LogCat，我将问题缩小到getActivity()方法。我也Log.d()输入了ViewAllSongsActivity.onCreate()，但该消息从未打印出来。当我自己运行时ViewAllSongsActivityTests，测试通过了。下面是测试的代码：

public class ViewAllSongsActivityTests extends ActivityInstrumentationTestCase2<ViewAllSongsActivity> {
    public ViewAllSongsActivityTests() {
        super(ViewAllSongsActivity.class);
    }

    public void testSongsAreLoaded() throws InstantiationException, IllegalAccessException, ClassNotFoundException {
        Activity activity = this.getActivity(); // this never returns
        ListView songList = (ListView) activity.findViewById(R.id.allSongsList);
        assertTrue(songList.getCount() > 0);
    }
}