Please read for an updated status on RailsCasts:
Learn more or hide this
GitHub User: SirRawlins
I came across this today when looking to test ActiveResource and it proved to work really nicely, however I then came across ActiveResource::HttpMock which is a specific mocking implementation for active resource which was even easier to get up and running.
Thanks for the cast though, set me on the right path of mocking the web request rather than the ActiveResource itself.