There is another question about effects of an expired developer: http://photo.stackexchange.com/questions/75369/what-are-the-effects-of-developing-film-with-an-expired-developer

How to determine, without sacrificing exposed film, if a developer for film (still in its bottle, opened) is still usable? And without using any film at all? can I use some other easy to find test material to verify the integrity of the chemical?