### Question:
BoundingBoxOverlay implements Overlay { @Override public void close() { myController.close(); } BoundingBoxOverlay(MapModel mapModel); @Override void close(); @Override void draw(Graphics graphics);  }### Answer:
@Test public void testClose() { MapModel mapModel = new MapModel(); BoundingBoxOverlay overlay = new BoundingBoxOverlay(mapModel); assertEquals(1, mapModel.countObservers()); overlay.close(); assertEquals(0, mapModel.countObservers()); }