Skipfish : Skipfish is an active web application security reconnaissance tool. It prepares an interactive sitemap for the targeted site by carrying out a recursi...
Diagnostic.css : Diagnostic.css is a stylesheet which allows the user to test for common errors in a page's markup.
Also : https://github.com/karlgroves/diagnostic.css
atoum : A simple, modern and intuitive unit testing framework for PHP!
Mink is an open source acceptance test framework for web applications, written in PHP 5.3.