使用Android Test Framework进行Android AsyncTask测试

Question

我有一个非常简单的AsyncTask实现示例,并且在使用Android JUnit框架测试它时遇到问题.

当我在普通应用程序中实例化并执行它时,它工作得很好.但是当它从任何Android测试框架类(即AndroidTestCase,ActivityUnitTestCase,ActivityInstrumentationTestCase2等)执行时,它表现得很奇怪:

• 它doInBackground()正确执行方法
• 然而,它没有任何调用它的通知方法(onPostExecute(),onProgressUpdate()等) -只是默默忽略它们没有表现出任何错误.

这是非常简单的AsyncTask示例:

package kroz.andcookbook.threads.asynctask;

import android.os.AsyncTask;
import android.util.Log;
import android.widget.ProgressBar;
import android.widget.Toast;

public class AsyncTaskDemo extends AsyncTask<Integer, Integer, String> {

AsyncTaskDemoActivity _parentActivity;
int _counter;
int _maxCount;

public AsyncTaskDemo(AsyncTaskDemoActivity asyncTaskDemoActivity) {
    _parentActivity = asyncTaskDemoActivity;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
    _parentActivity._progressBar.setVisibility(ProgressBar.VISIBLE);
    _parentActivity._progressBar.invalidate();
}

@Override
protected String doInBackground(Integer... params) {
    _maxCount = params[0];
    for (_counter = 0; _counter <= _maxCount; _counter++) {
        try {
            Thread.sleep(1000);
            publishProgress(_counter);
        } catch (InterruptedException e) {
            // Ignore           
        }
    }
}

@Override
protected void onProgressUpdate(Integer... values) {
    super.onProgressUpdate(values);
    int progress = values[0];
    String progressStr = "Counting " + progress + " out of " + _maxCount;
    _parentActivity._textView.setText(progressStr);
    _parentActivity._textView.invalidate();
}

@Override
protected void onPostExecute(String result) {
    super.onPostExecute(result);
    _parentActivity._progressBar.setVisibility(ProgressBar.INVISIBLE);
    _parentActivity._progressBar.invalidate();
}

@Override
protected void onCancelled() {
    super.onCancelled();
    _parentActivity._textView.setText("Request to cancel AsyncTask");
}

}

这是一个测试用例.这里AsyncTaskDemoActivity是一个非常简单的Activity,提供用于在模式下测试AsyncTask的UI:

package kroz.andcookbook.test.threads.asynctask;
import java.util.concurrent.ExecutionException;
import kroz.andcookbook.R;
import kroz.andcookbook.threads.asynctask.AsyncTaskDemo;
import kroz.andcookbook.threads.asynctask.AsyncTaskDemoActivity;
import android.content.Intent;
import android.test.ActivityUnitTestCase;
import android.widget.Button;

public class AsyncTaskDemoTest2 extends ActivityUnitTestCase<AsyncTaskDemoActivity> {
AsyncTaskDemo _atask;
private Intent _startIntent;

public AsyncTaskDemoTest2() {
    super(AsyncTaskDemoActivity.class);
}

protected void setUp() throws Exception {
    super.setUp();
    _startIntent = new Intent(Intent.ACTION_MAIN);
}

protected void tearDown() throws Exception {
    super.tearDown();
}

public final void testExecute() {
    startActivity(_startIntent, null, null);
    Button btnStart = (Button) getActivity().findViewById(R.id.Button01);
    btnStart.performClick();
    assertNotNull(getActivity());
}

}

所有这些代码都运行得很好,除了AsyncTask在Android Testing Framework中执行时不调用它的通知方法.有任何想法吗？

Answer 1

我在实现一些单元测试时遇到了类似的问题.我必须测试一些与Executors一起工作的服务,我需要让我的服务回调与我的ApplicationTestCase类中的测试方法同步.通常,测试方法本身在访问回调之前就已完成,因此不会测试通过回调发送的数据.尝试应用@UiThreadTest胸围仍然无法正常工作.

我找到了以下方法,该方法有效,我仍然使用它.我只是使用CountDownLatch信号对象来实现wait-notify(你可以使用synchronized(lock){... lock.notify();},但这会产生丑陋的代码)机制.

public void testSomething(){
final CountDownLatch signal = new CountDownLatch(1);
Service.doSomething(new Callback() {

  @Override
  public void onResponse(){
    // test response data
    // assertEquals(..
    // assertTrue(..
    // etc
    signal.countDown();// notify the count down latch
  }

});
signal.await();// wait for callback
}

Answer 2

我找到了很多很接近的答案,但没有一个能正确地将所有部分放在一起.因此,在JUnit测试用例中使用android.os.AsyncTask时,这是一个正确的实现.

 /**
 * This demonstrates how to test AsyncTasks in android JUnit. Below I used 
 * an in line implementation of a asyncTask, but in real life you would want
 * to replace that with some task in your application.
 * @throws Throwable 
 */
public void testSomeAsynTask () throws Throwable {
    // create  a signal to let us know when our task is done.
    final CountDownLatch signal = new CountDownLatch(1);

    /* Just create an in line implementation of an asynctask. Note this 
     * would normally not be done, and is just here for completeness.
     * You would just use the task you want to unit test in your project. 
     */
    final AsyncTask<String, Void, String> myTask = new AsyncTask<String, Void, String>() {

        @Override
        protected String doInBackground(String... arg0) {
            //Do something meaningful.
            return "something happened!";
        }

        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);

            /* This is the key, normally you would use some type of listener
             * to notify your activity that the async call was finished.
             * 
             * In your test method you would subscribe to that and signal
             * from there instead.
             */
            signal.countDown();
        }
    };

    // Execute the async task on the UI thread! THIS IS KEY!
    runTestOnUiThread(new Runnable() {

        @Override
        public void run() {
            myTask.execute("Do something");                
        }
    });       

    /* The testing thread will wait here until the UI thread releases it
     * above with the countDown() or 30 seconds passes and it times out.
     */        
    signal.await(30, TimeUnit.SECONDS);

    // The task is done, and now you can assert some things!
    assertTrue("Happiness", true);
}

Answer 3

处理此问题的方法是运行调用AsyncTask的任何代码runTestOnUiThread():

public final void testExecute() {
    startActivity(_startIntent, null, null);
    runTestOnUiThread(new Runnable() {
        public void run() {
            Button btnStart = (Button) getActivity().findViewById(R.id.Button01);
            btnStart.performClick();
        }
    });
    assertNotNull(getActivity());
    // To wait for the AsyncTask to complete, you can safely call get() from the test thread
    getActivity()._myAsyncTask.get();
    assertTrue(asyncTaskRanCorrectly());
}

默认情况下,junit在与主应用程序UI不同的单独线程中运行测试.AsyncTask的文档说任务实例和对execute()的调用必须在主UI线程上; 这是因为AsyncTask依赖于主线程Looper并且MessageQueue内部处理程序可以正常工作.

注意:

我以前建议@UiThreadTest在测试方法上使用它作为装饰器来强制测试在主线程上运行,但这对于测试AsyncTask不太正确,因为当你的测试方法在主线程上运行时,没有消息在main MessageQueue - 包括AsyncTask发送的有关其进度的消息,导致测试挂起.

Answer 4

如果您不介意在调用程序线程中执行AsyncTask(在单元测试的情况下应该没问题),您可以在当前线程中使用Executor,如/sf/answers/460870791/中所述

public class CurrentThreadExecutor implements Executor {
    public void execute(Runnable r) {
        r.run();
    }
}

然后在这样的单元测试中运行AsyncTask

myAsyncTask.executeOnExecutor(new CurrentThreadExecutor(), testParam);

这仅适用于HoneyComb及更高版本.

Answer 5

我为Android编写了足够多的unitests,只想分享如何做到这一点.

首先,这里是负责等待和释放服务员的助手类.没什么特别的:

SyncronizeTalker

public class SyncronizeTalker {
    public void doWait(long l){
        synchronized(this){
            try {
                this.wait(l);
            } catch(InterruptedException e) {
            }
        }
    }



    public void doNotify() {
        synchronized(this) {
            this.notify();
        }
    }


    public void doWait() {
        synchronized(this){
            try {
                this.wait();
            } catch(InterruptedException e) {
            }
        }
    }
}

接下来,让我们使用一个应该AsyncTask在工作完成时调用的方法创建接口.当然,我们也想测试我们的结果:

TestTaskItf

public interface TestTaskItf {
    public void onDone(ArrayList<Integer> list); // dummy data
}

接下来让我们创建一个我们要测试的Task的骨架:

public class SomeTask extends AsyncTask<Void, Void, SomeItem> {

   private ArrayList<Integer> data = new ArrayList<Integer>(); 
   private WmTestTaskItf mInter = null;// for tests only

   public WmBuildGroupsTask(Context context, WmTestTaskItf inter) {
        super();
        this.mContext = context;
        this.mInter = inter;        
    }

        @Override
    protected SomeItem doInBackground(Void... params) { /* .... job ... */}

        @Override
    protected void onPostExecute(SomeItem item) {
           // ....

       if(this.mInter != null){ // aka test mode
        this.mInter.onDone(data); // tell to unitest that we finished
        }
    }
}

最后 - 我们最潇洒的课程:

TestBuildGroupTask

public class TestBuildGroupTask extends AndroidTestCase  implements WmTestTaskItf{


    private SyncronizeTalker async = null;

    public void setUP() throws Exception{
        super.setUp();
    }

    public void tearDown() throws Exception{
        super.tearDown();
    }

    public void test____Run(){

         mContext = getContext();
         assertNotNull(mContext);

        async = new SyncronizeTalker();

        WmTestTaskItf me = this;
        SomeTask task = new SomeTask(mContext, me);
        task.execute();

        async.doWait(); // <--- wait till "async.doNotify()" is called
    }

    @Override
    public void onDone(ArrayList<Integer> list) {
        assertNotNull(list);        

        // run other validations here

       async.doNotify(); // release "async.doWait()" (on this step the unitest is finished)
    }
}

就这样.

希望它对某人有所帮助.