Unit Tests Are a Tax on Refactoring and Redesign

unit tests are more or less a tax on refactoring and redesign since the unit tests may need to be rewritten as well. If you have a module that is, has lots of unit tests and you realize, oh, the design of this module is not quite right,. You will have to rewrite unit tests to achieve that. So it will take you more effort to write the new code. But just like writing the fresh code in the first place, the point is not to just get code written.