Sebastian Bergmann talks about a new bit of functionality he's put into the 3.4 release of PHPUnit (the popular unit testing tool for PHP) based on a suggestion from a paper he'd read:

Back in July, I came across an academic paper (more academic papers on testing that I read recently) titled "JExample: Exploiting Dependencies Between Tests to Improve Defect Localization". [...] For the upcoming PHPUnit 3.4 I have implemented support for the idea expressed in the paper mentioned above.

The feature is a system that helps localize problems at the source, stripping away all of the cascading issues it might have tripped off, causing other tests to fail. This new feature (as illustrated by his code example using a DependencyFailureTest class) makes it simple to fail a test immediately whenever the scripts needs to via a fail() method. Check out the full post for the rest of the code and some further explanation on how it works.