### Question:
DisplayHierarchy { public void expand() { DisplayHierarchyContext context = initialiseContext(); while (!context.completed()) { DisplayHierarchyNode node = context.queue().remove(); expandNode( context, node ); annotateNodes( context, node ); } } DisplayHierarchy( Page page ); List<DisplayHierarchyNode> roots(); void expand();  }### Answer:
@Test public void testExpand() { DisplayHierarchy dh = fixture1(); dh.expand(); assertEquals( 10, dh.roots().size() ); }
@Test public void testExplicitPaths() { DisplayHierarchy dh = fixture2(); dh.expand(); }