The review that made me a better engineer

Three years ago a staff engineer reviewed a pull request of mine and left two sentences. The first was a question about a race condition I had missed. The second was a link to a test that would have caught it.

I remember feeling annoyed for about ten minutes. Then I realized the review was not about the code. It was about the shape of my attention. I had tested the happy path thoroughly and the edges not at all.

Since then I keep a small checklist at the top of every pull request: what happens on retry, what happens when the list is empty, what happens when the user is on a slow connection. None of it is exotic. All of it is where the bugs live.

The best review I ever got did not make the code shorter or cleverer. It made me a slightly more suspicious person, in the useful way. If you are lucky enough to get a review like that, print it out.