### Question:
Handler implements Handlables, Updatable, Renderable, IdentifiableListener, Listenable<HandlerListener> { @Override public final Featurable get(Integer id) { Featurable featurable = featurables.get(id); if (featurable == null) { featurable = toAdd.get(id); } if (featurable != null) { return featurable; } throw new LionEngineException(ERROR_FEATURABLE_NOT_FOUND + String.valueOf(id)); } Handler(Services services); final void addComponent(ComponentUpdater component); final void addComponent(ComponentRenderer component); final void add(Featurable featurable); final void remove(FeatureProvider featurable); final void removeAll(); final int size(); void updateAdd(); void updateRemove(); @Override final void addListener(HandlerListener listener); @Override final void removeListener(HandlerListener listener); @Override final Featurable get(Integer id); @Override Iterable<I> get(Class<I> type); @Override Iterable<Featurable> values(); @Override void update(double extrp); @Override void render(Graphic g); @Override final void notifyDestroyed(Integer id);  }### Answer:
@Test void testObjectIdNotFound() { assertThrows(() -> handler.get(Integer.valueOf(0)), Handler.ERROR_FEATURABLE_NOT_FOUND + 0); }
@Test void testObjectTypeNotFound() { assertFalse(handler.get(Featurable.class).iterator().hasNext()); }