Testing rendered output

I would like to check that one of the methods in my controller
produces the expected rendered output. The method in question just
returns a JSON string, so it's not like I'm trying to check a whole
web page or something. Is there a way to get the rendered output
somehow? I looked at the TestResponse methods (checking the source)
and there didn't seem to be anything useful there.

Thanks,
      --Paul

response.body should let you get at the string.