UiScrollable bug

what's wrong ?

UiScrollbale.getChildByText() sometime will scroll a little , and make the devices can't find the right uiobject in screen , finally throw UiObjectNotFoundException.

The root cause may be from system .

flow

When you call the getChildByText() , its flow is :

getChildByText -> scrollIntoView -> scrollForward -> scrollSwipe

In scrollSwipe , system will run swipe command , wait , than find all AccessibilityEvent and filter AccessibilityEvent.TYPE_VIEW_SCROLLED in current screen. This step make UiScrollable scroll again or check it in the end.

But the bug is here , system can't return right AccessibilityEvent .

public boolean scrollSwipe(final int downX, final int downY, final int upX, final int upY, final int steps) 
 { 
Runnable command = new Runnable() { 
    @Override public void run() 
   {swipe(downX, downY, upX, upY, steps);} 
  }; 

   // Collect all accessibility events generated during the swipe command and get the last event
   ArrayList<AccessibilityEvent> events = new ArrayList<AccessibilityEvent>(); 

   runAndWaitForEvents(command, new
   EventCollectingPredicate(AccessibilityEvent.TYPE_VIEW_SCROLLED, events), 
   Configurator.getInstance().getScrollAcknowledgmentTimeout());

    //**Root cause**
    //Some times the events list size will be 0 ,
    //but in fact it can scroll again. 
    Log.e(LOG_TAG,"events size = " + events.size()); 

    AccessibilityEvent event = getLastMatchingEvent(events,
         AccessibilityEvent.TYPE_VIEW_SCROLLED); 

    if (event == null) { 
     // end of scroll since no new scroll events received
     recycleAccessibilityEvents(events);
     return false; 
     } 
...
..
. 
}

solve

I think the best way is that Overriding the code and defining the suitable MaxSearchSwipes , and if the item is over this size , make the test fail.

public class UiScrollableFix extends UiScrollable {
public UiScrollableFix(UiSelector container) 
{ super(container); }

 @Override
 public boolean scrollIntoView(UiSelector selector) throws UiObjectNotFoundException { 
  Tracer.trace(selector);
  // if we happen to be on top of the text we want then return here UiSelector 
  childSelector = getSelector().childSelector(selector); 
  if (exists(childSelector)) { 
  return (true); 
   } else {  
  // we will need to reset the search from the beginning to start search     
  scrollToBeginning(getMaxSearchSwipes());
  if (exists(childSelector)) { 
  return (true); }

  for (int x = 0; x < getMaxSearchSwipes(); x++) { 
  boolean scrolled = scrollForward(); 
  if (exists(childSelector)) { 
   return true; 
   }

       //For avoiding the scroll fail.
       // if (!scrolled && x!=0) {
       //return false;
       // }
   }
 } 
return false; 
}
}