Don't Look Right At the Sun

When you want to see an eclipse, you don't look directly at the sun. You look around the sun.

Testing is much the same way. I find most of my bugs in peripheral vision, not directly in the thing I thought I was testing. I wrote about this a while ago: seeing around the problem.

I have a really hard time teaching other people about this. Some people just get it; others don't. How do you teach someone to see a bug when they're looking at something just next to it?