### Question:
OverlayView implements ExpandedView.ExpandedViewCallback { void updateExpandedView(List<Page> pages, Page selected) { expandedView.displayPages(pages, selected, false); } OverlayView(Context context, DragHelper dragHelper, ExpandedView expandedView); @Override void finish(); @Nullable @Override View findViewById(int id); @Override void onPageSelected(Page page);  }### Answer:
@Test public void updateExpandedView() { final List<Page> pages = IntStream.range(0, 5).mapToObj(this::createPage).collect(Collectors.toList()); view.updateExpandedView(pages, pages.get(1)); verify(expandedView).displayPages(eq(pages), eq(pages.get(1)), eq(false)); }