### Question:
BoundingBoxController implements Observer { public void close() { myModel.deleteObserver(this); myMapModel.deleteObserver(this); } BoundingBoxController(MapModel mapModel, BoundingBoxModel model); void close(); @Override void update(Observable o, Object arg);  }### Answer:
@Test public void testClose() { MapModel mapModel = new MapModel(); mapModel.setHeightWidth(400, 400); BoundingBoxModel model = new BoundingBoxModel(); BoundingBoxController controller = new BoundingBoxController(mapModel, model); assertEquals(1, mapModel.countObservers()); assertEquals(1, model.countObservers()); controller.close(); assertEquals(0, mapModel.countObservers()); assertEquals(0, model.countObservers()); }