### Question:
DefaultContainerCascade implements ContainerCascade { @Override public void addTo(PolygonPanel panel) { for (IdentifiedPolygon node : nodes) { node.element.setText(node.id); panel.add((InteractiveGraphicsElement) node.element); } for (FlexibleArrow edge : edges) { panel.add(edge); } }  void add(final IdentifiedPolygon node); void add(FlexibleArrow element); @Override void colorNode(String nodeId, RGBColor fillColor); @Override void addTo(PolygonPanel panel); @Override void addToggleListener(NodeToggleListener listener); @Override void removeToggleListener(NodeToggleListener listener); @Override void initNodeNames(NodePresentationProperties properties); @Override void determinePositionFor(String nodeId, ShapeWithPosition control); @Override boolean hasNode(String nodeId); void moveBy(double x, double y);  }### Answer:
@Test public void setsNodeIdAsTextOnPolygon() throws Exception { PolygonPanel panel = mock(PolygonPanel.class); container.addTo(panel); verify(polygon1).setText("X"); }