Debugging Tools in VC#

I'm working on a managed DirectX project in Visual C# 2005 professional. It has swelled to over 15 classes, and I'm working on debugging it.

I think it would be neat to have a feature where I could just run a single function in a sort of sandox, and be able to just give it diffrent inputs and check the outputs to get a good sense of how it works. I know I could move it to a diffrent file, and then run it there with some textboxes on screen. But that has a few problems.

1. Its terribly inconvenient for testing numerous functions
2. If I have an exception thrown that crashes the program, I won't see the output.

So does such a feature exist, where I can cleanly enter preconditions for a functions and see a list of post-conditions.

If no such thing exists, are there any alternative debugging features in Studio that you've found to be useful for large projects.