A JUnit extension that lets you stub out concrete classes during unit tests. For JUnit 3, you use {@link us.blanshard.stubout.StubbingTestCase} as the base class for your unit tests. For JUnit 4, you use {@link us.blanshard.stubout.StubbingRunner} to run your unit test class. In both cases, you call static methods on {@link us.blanshard.stubout.Stubber} to tell StubOut which classes to stub out and how.