Using TDD to drive out thread-safe code

Question

What\'s a good way to leverage TDD to drive out thread-safe code? For example, say I have a factory method that utilizes lazy initialization to create only one instance of

Answer 1

Just off the top of my head could you compare the instances returned to see if they are indeed the same instance or if they are different? That's probably where I would start with C#, I would imagine you can do the same in java