问题
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?
回答1:
This is happening because the Espresso scrollTo() method explicitly checks the layout class and only works for ScrollView & HorizontalScrollView. Internally it's using View.requestRectangleOnScreen(...) so I'd expect it to actually work fine for many layouts.
My workaround for NestedScrollView was to take ScrollToAction and modify that constraint. The modified action worked fine for NestedScrollView with that change.
Changed method in ScrollToAction class:
public Matcher<View> getConstraints() {
return allOf(withEffectiveVisibility(Visibility.VISIBLE), isDescendantOfA(anyOf(
isAssignableFrom(ScrollView.class), isAssignableFrom(HorizontalScrollView.class), isAssignableFrom(NestedScrollView.class))));
}
Convenience method:
public static ViewAction betterScrollTo() {
return ViewActions.actionWithAssertions(new NestedScrollToAction());
}
回答2:
Here is how I did the same thing that @miszmaniac did in Kotlin. With delegation in Kotlin, it is much cleaner and easier because I don't have to override the methods I don't need to.
class ScrollToAction(
private val original: android.support.test.espresso.action.ScrollToAction = android.support.test.espresso.action.ScrollToAction()
) : ViewAction by original {
override fun getConstraints(): Matcher<View> = anyOf(
allOf(
withEffectiveVisibility(Visibility.VISIBLE),
isDescendantOfA(isAssignableFrom(NestedScrollView::class.java))),
original.constraints
)
}
回答3:
I had this issue with CoordinatorLayout->ViewPager->NestedScrollView an easy work around from me to get the same scrollTo() behavior was to just swipe up on the screen:
onView(withId(android.R.id.content)).perform(ViewActions.swipeUp());
回答4:
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_behaviorlayout 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:
- Making a custom scrollTo() action (as referenced by the OP and Turnsole)
- Removing the NestedScrollView's layout params as shown here
回答5:
Barista's scrollTo(R.id.button) works on all kinds of scrollable views, also on NestedScrollView.
It's useful to fix this kind of issues with Espresso. We develop and use it just to write Espresso tests in a fast and reliable way. And here's a link: https://github.com/SchibstedSpain/Barista
回答6:
I've made a NestedScrollViewScrollToAction class.
I think it's better place to make activity specific stuff there instead.
The only thing worth mentioning is that code searches for parent nestedScrollView and removes it's CoordinatorLayout behaviour.
https://gist.github.com/miszmaniac/12f720b7e898ece55d2464fe645e1f36
回答7:
The solution of Mr Mido may work in some situations, but not always. If you have some view in the bottom of screen, the scroll of your RecyclerView will not happen because the click will start outside the RecyclerView.
One way to workaround this problem is to write a custom SwipeAction. Like this:
1 - Create the CenterSwipeAction
public class CenterSwipeAction implements ViewAction {
private final Swiper swiper;
private final CoordinatesProvider startCoordProvide;
private final CoordinatesProvider endCoordProvide;
private final PrecisionDescriber precDesc;
public CenterSwipeAction(Swiper swiper, CoordinatesProvider startCoordProvide,
CoordinatesProvider endCoordProvide, PrecisionDescriber precDesc) {
this.swiper = swiper;
this.startCoordProvide = startCoordProvide;
this.endCoordProvide = endCoordProvide;
this.precDesc = precDesc;
}
@Override public Matcher<View> getConstraints() {
return withEffectiveVisibility(ViewMatchers.Visibility.VISIBLE);
}
@Override public String getDescription() {
return "swipe from middle of screen";
}
@Override
public void perform(UiController uiController, View view) {
float[] startCoord = startCoordProvide.calculateCoordinates(view);
float[] finalCoord = endCoordProvide.calculateCoordinates(view);
float[] precision = precDesc.describePrecision();
// you could try this for several times until Swiper.Status is achieved or try count is reached
try {
swiper.sendSwipe(uiController, startCoord, finalCoord, precision);
} catch (RuntimeException re) {
throw new PerformException.Builder()
.withActionDescription(this.getDescription())
.withViewDescription(HumanReadables.describe(view))
.withCause(re)
.build();
}
// ensures that the swipe has been run.
uiController.loopMainThreadForAtLeast(ViewConfiguration.getPressedStateDuration());
}
}
2 - Create the method to return the ViewAction
private static ViewAction swipeFromCenterToTop() {
return new CenterSwipeAction(Swipe.FAST,
GeneralLocation.CENTER,
view -> {
float[] coordinates = GeneralLocation.CENTER.calculateCoordinates(view);
coordinates[1] = 0;
return coordinates;
},
Press.FINGER);
}
3 - Then use it to scroll the screen:
onView(withId(android.R.id.content)).perform(swipeFromCenterToTop());
And that's it! This way you can control how the scroll is going to happen in your screen.
来源：https://stackoverflow.com/questions/35272953/espresso-scrolling-not-working-when-nestedscrollview-or-recyclerview-is-in-coor