Selenium-on-Rails - is a test tool for web applications. Selenium tests run directly in a browser, just as real users do. And they run in Internet Explorer, Mozilla and Firefox on Windows, Linux, and Macintosh. No other test tool covers such a wide array of platforms.

Watir (Web Application Testing in Ruby) - Watir drives Internet Explorer the same way people do. It clicks links, fills in forms, presses buttons. Watir also checks results, such as whether expected text appears on the page.

RubyonRails - Ruby on Rails is an open-source web framework that's optimized for programmer happiness and sustainable productivity.