Espresso, scrolling not working when NestedScrollV

Question

It looks like CoordinatorLayout breaks the behaviour of Espresso actions such as scrollTo() or RecyclerViewActions.scrollToPosition().

Issue with NestedScrollView

For a layout like this one:

<android.support.design.widget.CoordinatorLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        ...

    </android.support.v4.widget.NestedScrollView>

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        ...

    </android.support.design.widget.AppBarLayout>

</android.support.design.widget.CoordinatorLayout>

If I try to scroll to any view inside the NestedScrollView using ViewActions.scrollTo() the first problem I find is that I get a PerformException. This is because this action only supports ScrollView and NestedScrollView doesn't extend it. A workaround for this problem is explained here, basically we can copy the code in scrollTo() and change the constrains to support NestedScrollView. This seems to work if the NestedScrollView is not in a CoordinatorLayout but as soon as you put it inside a the CoordinatorLayout the scrolling action fails.

Issue with RecyclerView

For the same layout, if I replace the NestedScrollView with a RecyclerView there is also problems with the the scrolling.

In this case I'm using RecyclerViewAction.scrollToPosition(position). Unlike the NestedScrollView, here I can see some scrolling happening. However, it looks like it scrolls to the wrong position. For example, if I scroll to the last position, it makes visible the second to last but not the last one. When I move the RecyclerView out of the CoordinatorLayout the scrolling works as it should.

At the moment we can't write any Espresso test for the screens that use CoordinatorLayout due to this issues. Anyone experiencing the same problems or knows a workaround?

Answer 1

This issue has been reported (perhaps by the OP?), see Issue 203684

One of the comments to that issue suggests a work-around to the problem when the NestedScrollView is inside of a CoordinatorLayout:

you need to remove the @string/appbar_scrolling_view_behavior layout behaviour of the ScrollingView or any parent view this ScrollingView is included in

Here is an implementation of that work-around:

    activity.runOnUiThread(new Runnable() {
        @Override
        public void run() {
            // remove CoordinatorLayout.LayoutParams from NestedScrollView
            NestedScrollView nestedScrollView = (NestedScrollView)activity.findViewById(scrollViewId);
            CoordinatorLayout.LayoutParams params =
                    (CoordinatorLayout.LayoutParams)nestedScrollView.getLayoutParams();
            params.setBehavior(null);
            nestedScrollView.requestLayout();
        }
    });

I was able to get my tests working by:

1. Making a custom scrollTo() action (as referenced by the OP and Turnsole)
2. Removing the NestedScrollView's layout params as shown here