[bluejekyll]

This is true of any code you throw out. If you throw out the code, you should definitely throw out the corresponding tests.

It doesn't invalidate the fact that unit tests increase your confidence in your own code.

[ryanbrunner]

The point is, as your tests get more and more fine grained, and the units themselves get more and more fine grained (in my experience these go hand-in-hand with a TDD approach), the changes that the units themselves maintain intact approaches zero, because otherwise the only refactorings possible are completely trivial.