Write that first complicated test

What code of yours isn’t tested? Is it code that deals with complicated situations that you don’t control? Threads, running commands, git, networking, or UI?

Our apps are most interesting when they’re complicated. They’re also most dangerous. And that’s why code that’s hard to test is exactly the kind of code that needs to be tested well. That doesn’t always happen.

Instead, every time you touch that code, you touch lightly. You tread carefully. Maybe you do some manual testing. And when you...