Avoiding change has other bad consequences. When people don’t make changes often they get rusty at it. Breaking down a big class into pieces can be pretty involved work unless you do it a couple of times a week. When you do, it becomes routine. You get better at figuring out what can break and what can’t, and it is much easier to do.
Other kinds of tests often masquerade as unit tests. A test is not a unit test if: 1. It talks to a database. 2. It communicates across a network. 3. It touches the file system. 4. You have to do special things to your environment (such as editing configuration files) to run it. Tests that do these things aren’t bad. Often they are worth writing, and you generally will write them in unit test harnesses. However, it is important to be able to separate them from true unit tests so that you can keep a set of tests that you can run fast whenever you make changes.
1. Identify change points. 2. Find test points. 3. Break dependencies. 4. Write tests. 5. Make changes and refactor.