It begins like many stories in software: a well-intentioned developer joining a project, determined to do things properly. You arrive at a codebase that has grown organically, perhaps even chaotically. You decide you will bring order. You set up unit testing, you configure continuous integration, you measure code coverage. You write dozens or hundreds of tests. Every public method is touched, every branch is at least executed. The dashboard lights up green. You feel, quite frankly, on top of things.
Then one day, production breaks under your watch



