### Question:
OverlayView implements ExpandedView.ExpandedViewCallback { void setSelectedPage(Page page) { expandedView.setSelected(page); } 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 setSelectedPage() { final Page page = createPage(1); view.setSelectedPage(page); verify(expandedView).setSelected(eq(page)); }