JUnit.org Resources for Test Driven Development

Accessive is a tool that allows you to access private field or methods for testing purposes. That means that you don't have to make some of your methods or field package protected just to allow for testing.
Accessive uses reflection and dynamic proxies to access private portion of your objects, allowing you to keep them strongly encapsulated and still be able to test their internals.

For more details visit http://code.google.com/p/accessive/.