How can I perform a multi touch swipe with Espresso?

Question

How can I perform a multi touch swipe with Espresso? e.g. a two finger swipe to the right.

Answer 1

As @Daniel suggested, I created a custom version of MotionEvents, because when using multiple fingers you have to inject ACTION_POINTER_DOWN/UP instead of ACTION_DOWN/UP. And I created a twoFinger version of LinearSwipe, like this:

private static Swiper.Status sendLinearSwipe(UiController uiController,
                                             float[] startCoordinates,
                                             float[] startCoordinatesSecondFinger,
                                             float[] endCoordinates,
                                             float[]endCoordinatesSecondFinger,
                                             float[] precision,
                                             float[] precisionSecond,
                                             int duration) {
    checkNotNull(uiController);
    checkNotNull(startCoordinates);
    checkNotNull(startCoordinatesSecondFinger);
    checkNotNull(endCoordinates);
    checkNotNull(endCoordinatesSecondFinger);
    checkNotNull(precision);
    checkNotNull(precisionSecond);

    float[][] steps = interpolate(startCoordinates, endCoordinates, SWIPE_EVENT_COUNT);
    float[][] stepsSecondFinger = interpolate(startCoordinatesSecondFinger, endCoordinatesSecondFinger, SWIPE_EVENT_COUNT);
    final int delayBetweenMovements = duration / steps.length;
    final int delayBetweenMovementsSecondFinger = duration / stepsSecondFinger.length;

    int maxLength=Math.min(steps.length, stepsSecondFinger.length);

    MotionEvent downEvent;
    downEvent = MotionEvents.sendDown(uiController, steps[0], precision,true).down;
    MotionEvent downEventSecondFinger;
    downEventSecondFinger = MotionEvents.sendDown(uiController,stepsSecondFinger[0], precisionSecond,false).down;

    try {
        for (int i = 1; i < maxLength; i++) {

            if (sendMovement(uiController, steps[i], downEvent)) return Status.FAILURE;
            if (sendMovement(uiController, stepsSecondFinger[i], downEventSecondFinger)) return Status.FAILURE;


            long desiredTime = downEvent.getDownTime() + delayBetweenMovements * i;
            long desiredTimeSecondFinger = downEventSecondFinger.getDownTime() + delayBetweenMovementsSecondFinger * i;

            long timeUntilDesired = desiredTime - SystemClock.uptimeMillis();
            long timeUntilDesiredSecondFinger = desiredTimeSecondFinger - SystemClock.uptimeMillis();
            loopMainThread(uiController, timeUntilDesired);
            loopMainThread(uiController, timeUntilDesiredSecondFinger);

        }

        if (!MotionEvents.sendUp(uiController, downEventSecondFinger, endCoordinatesSecondFinger,false)) {
            Log.e(TAG, "Injection of up event as part of the swipe failed. Sending cancel event.");
            MotionEvents.sendCancel(uiController, downEventSecondFinger);
            return Swiper.Status.FAILURE;
        }
    } finally {
        downEvent.recycle();
        downEventSecondFinger.recycle();
    }
    return Swiper.Status.SUCCESS;
}

private static void loopMainThread(UiController uiController, long timeUntilDesired) {
    if (timeUntilDesired > 10) {
        uiController.loopMainThreadForAtLeast(timeUntilDesired);
    }
}

private static boolean sendMovement(UiController uiController, float[] step, MotionEvent downEvent) {
    if (!MotionEvents.sendMovement(uiController, downEvent, step)) {
        Log.e(TAG, "Injection of move event as part of the swipe failed. Sending cancel event.");
        MotionEvents.sendCancel(uiController, downEvent);
        return true;
    }
    return false;
}

Now it works perfectly! Thanks @Daniel