I use a debugger. If you've got some input that gets transformed into unexpected output, it's great to follow the code along. Of course, placing debug output wo

I use a debugger. If you've got some input that gets transformed into unexpected output, it's great to follow the code along. Of course, placing debug output works too, be the debugger is usually faster in this situation. It's good for white box testing. It's also good for compiled languages. You know something is wrong, but you don't know why it's wrong.