Data fixtures for non-activerecord models

I have a model that as an instance maintains a session on a website, and
has
methods to return some scraped data. Instead of hitting a URL over and
over
during testing, I would like to just save the source to a file and use
that
like a fixture. A mock object doesn’t seem appropriate, because there
is a
lot of data here. What I’m doing now is storing each separate “fixture”
in
the directory fixtures/modelnames. I can’t imagine I’m the first person
to
have a model that maintains data, but does not extend activerecord.
What do
you guys do for this?

Thank you,
Zack