### Question:
WorldServerMessageFactory extends ServerMessageFactory { public Message generateNewlyInvisibleMessage(WorldObject object) { Message newlyInvisibleMessage = MessageRegistry.getInstance().createMessage("ObjectInvisibleMessage"); newlyInvisibleMessage.setArgument("id", object.getId()); return newlyInvisibleMessage; }  Message generateNewlyVisibleMessage(WorldObject object); List<Message> generateChangeStateMessages(Actor changedActor); Message generateForcedStateMessage(MoveState forcedState); Message generateActorMoveSpeedMessage(double moveSpeed); Message generateNewlyInvisibleMessage(WorldObject object); Message generateWorldLoginResponse(); Message generateWorldFileResponse(byte[] worldFileBytes); Message generateWorldChecksumResponse(byte[] checkSum);  }### Answer:
@Test public void testGenerateNewlyInvisibleMessage() { WorldObject o = mock(WorldObject.class); when(o.getId()).thenReturn(2468); Message message = worldServerMessageFactory.generateNewlyInvisibleMessage(o); assertEquals(message.name, "ObjectInvisibleMessage"); assertEquals(message.getArgument("id"), 2468); }