Test Callback in an activity with Robolectric

I have issues to test a callback in an activity using Robolectric.

I have one activity :

public class MainActivity extends Activity {
public static String value;
public Handler sHandler;

public Handler.Callback sHandlerCallback = new Handler.Callback(){

    @Override
    public boolean handleMessage(Message msg) {

        value = "SEND_REQUEST_MSG";
        changeName();
        return true;

    }

};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    final Button button = (Button) findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            sendMessage();
        }
    });

    HandlerThread handlerThread = new HandlerThread("estat");
    handlerThread.start();
    sHandler = new Handler(handlerThread.getLooper(), sHandlerCallback);

}

public void sendMessage()
{
    sHandler.obtainMessage().sendToTarget();
}

public void changeName()
{
    runOnUiThread (new Thread(new Runnable() {
        public void run() {
            TextView t= (TextView)findViewById (R.id.textToDisplay);
            t.setText(value);
        }
    }));

}}

and one test using Robolectric :

@RunWith(CustomRobolectricRunner.class)
public class TestApplicationTest {

private MainActivity activity;

@Test
public void testCreateMainActivity() throws InterruptedException {

    activity = Robolectric.buildActivity(MainActivity.class).create().get();

    Button pressMeButton = (Button) activity.findViewById(R.id.button);

    pressMeButton.performClick();

    Robolectric.runBackgroundTasks();
    Robolectric.runUiThreadTasksIncludingDelayedTasks();

    assertEquals("SEND_REQUEST_MSG", activity.value);

}}

So the fact is when I launch the activity from my phone, when I click the button specified in the activity we call the method sendMessage and add a Message to the queue. This message is handle by the method handleMessage in the callback which change the attribute value and call ChangeName().

But when I execute the test from command line with ./gradlew clean build. The test fails with an assertion error that tells me the value is null !

So can we test callBack with Robolectric ?

Thanks you very much !