The Maintainability of Unit Tests

At speakerconf 2010 discussion repeatedly arose around the idea that unit tests hinder your ability to refactor and add new features. It's true that tests are invaluable when refactoring the internals of a class as long as the interface doesn't change. However, when the interface does change, updating the associated tests is often the vast majority of the effort. Additionally, if a refactoring changes the interaction between two or more classes, the vast majority of the time is spent fixing t...