On the Synfony project's blog, they've posted about a new testing framework that they've implemented for their framework based around something they call "lime".
If you keep an eye on the timeline, you probably saw that the symfony unit tests have been completely reworked lately. This is because we switched from simpletest, which was fine but had side effects when functional tests were executed all at once, to our own testing framework, lime.
Lime is more lighweight than PHPUnit or simpletest and has several advantages. First, it launches test files in a sandbox to avoid strange effects between each test file run (one of the reasons we were unable to fix the old symfony core tests). It also introduces a new sfBrowser, sfTestBrowser and more importantly sfDomCssSelectorBrowser that allow you to write functionnal tests with ease. It is not backward compatible but is a lot more powerful than the old system. Oh, and it holds in a single file, lime.php, without any dependence.
They show some examples of its usage (and a note on which tests will need to be updated) as well as the output that would come of it. They've also included some sample tests (in the "test/" folder of the release) if you'd like to check it out more throughly.