Ah Ajax... the bane of automated and performance testers everywhere. Commercial testing tools don't really support it, and open source tools require real programmers to make it work. It's a great problem. Lucky for me, I think that all automated testers should be programmers in disguise, so I don't have a problem recommending solutions that require someone to get in and get their hands dirty.
Here are some places to start. And I say "places to start" and not "here are some tools" because that really depends on your specific application and how your developers have implemented Ajax. The two tools I would encourage you to start with are Selenium and Watir. I'm a huge fan of both and use them both regularly. If you're not familiar with the tools you can read about them on their Web sites. They're fairly easy to set up and get running. I think they're very easy to use.
So my recommendation? I would probably say start with Selenium (unless you really like Ruby). Get the tool setup. Use it to get some non-Ajax tests up and running. Then look at what you need to do to test your application's Ajax components. You may find it fairly easy, or it could be painful. That depends on what the application does, what you need to test, and the programming ability of the person writing the test.
This was first published in August 2007