We’ve been using this fine tool from Thoughtbot to test some of our own Rails applications, and we highly recommend it.
The traditional problem with browser-based testing frameworks (like Selenium, watir, webkit, envjs, etc.) is that they’re slow. Tests often take 30-60 seconds to run, each! That’s fine when you’re just starting a project, but after a few weeks of development, you could be waiting an hour or more for your tests to finish. With Tddium, those tests run in parallel in a few minutes, and they don’t hog the CPU on your laptop or workstation, freeing you to get back to work (or Facebook, or turntable.fm, or …).
We’ll round out our capybara testing capabilities in our next rollout, when we’ll offer Selenium 2 (in addition to the Selenium RC support we’ve had for several weeks). Stay tuned!