[caw]

It's a horrible sin for people who have to debug other people's code (read: team projects). Normally this team will have style guidelines on how to test, what to test, etc.

My view is that for personal projects and limited scope code you don't have to write any tests. I'm part of an operations team and nothing from the immediate team has test coverage. It's all Perl and shell scripts. Never have I thought "We need more test coverage", and I'm pretty sure only 1-2 people know of TDD. By the time you write the tests (for whatever reason it always takes me forever to get a test harness working with my code and IDE), you could have finished the code, tested it manually, and used it. If anything, I'd go back and write the test coverage before you redesign it, so you ensure functionality is the same before and after.