Saving graphs from puppet-catalog-test runs?

[Matt W]

When we run our puppet-catalog-test runs (https://github.com/invadersmustdie/puppet-catalog-test), we'd like to generate and save the .dot graph files so that we can turn them into images. I don;t know enough about the internal workings of Ruby/Puppet to do this -- but does anyone have any ideas? I'm sure it will require patching puppet-catalog-test.