### Question:
BackgroundModel extends Observable { public void add(Collection<TileGeometry> geometry) { myGeometries.addAll(geometry); setChanged(); notifyObservers(GEOMETRIES_PROP); }  void add(Collection<TileGeometry> geometry); Collection<TileGeometry> getGeometries(); List<Double> getGeometryScaleFactors(); void remove(Collection<TileGeometry> geometry); static final String GEOMETRIES_PROP; }### Answer:
@Test public void testAdd() { EasyMockSupport support = new EasyMockSupport(); BackgroundModel model = new BackgroundModel(); Observer observer = createObserver(support, model); support.replayAll(); model.addObserver(observer); TileGeometry[] geometries = createGeometries(); model.add(New.list(geometries)); assertEquals(2, model.getGeometries().size()); assertTrue(model.getGeometries().contains(geometries[0])); assertTrue(model.getGeometries().contains(geometries[1])); support.verifyAll(); }