Neither, I spend more time writing or thinking about tests. When I was earlier in my career I used to insert debug comments, run code, look at output to figure out what was going on. Now, I try to write my tests that will eliminate the need to debug. If I'm trying to fix a bug, the first thing I do is write tests for what should happen if the tests don't already exist and work backwards from there. If you get in a good habit of this, it just becomes natural and with today's toolchains you can re-run tests with a watcher to achieve a real time feedback loop, which is better than a debugger IMO. The plus side is going forward you always know that the code works vs just seeing it work that one time. As your application grows, something may change what the value of the debug statement output and you'll never catch it, but your test will. /old man rant