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.