I've built a simple little system that I'm using to automate creating tests of my client's website.
You simply start the proxy daemon and browse normally with your browser set to use that proxy.
It's output are (nearly) fully formed test scripts that can be run to verify that your website works as expected.
All that's needed is to add a "verifier" to each script to do your validation checking. The means of interacting with the website to get it to the point of being validated is all generated for you!