ScalaCheck is allows you to write tests at the high level of "properties," leaving the generation of test data that actual checks the properties to the tool. ScalaCheck is an open source project available here:
The author of ScalaCheck, Rickard Nilsson, is the author of ScalaCheck: The Definitive Guide, which shows how (and why) property-based testing is different from traditional testing approaches, and shows how to use the library effectively.