Automated test for links between models

Hey, I've got plenty of models that are interconnected by methods:

belongs_to
has_many
has_one
and :through

I've created all of the models first, and now I have the headache to
test that all of the links work properly. I've been wondering if
there's any gem or plugin that would do it automatically? By just
specifying the links with some meta language and than it would
automatically build all the tests?
Any suggestions?

Cheers,

michau