How is unit testing fun?

I tried today to do some unit testing with c code using the check frame work. I could not get it to work. Honestly, I don't see why people who are doing programming for fun, and for free decide to do something so unfun like unit testing. Also people go on and on about how important it is, but as a developer, I don't really find the check framework or explanation to be much fun.
The irony is I've known some professional programmers who never had to do any unit testing at work, yet why do people do unit testing when they come home when it doesn't seem to be a great joy. Can some one explain the unit test fun, particularly the make check framework for c unit tests?
The irony is I've known some professional programmers who never had to do any unit testing at work, yet why do people do unit testing when they come home when it doesn't seem to be a great joy. Can some one explain the unit test fun, particularly the make check framework for c unit tests?