Author here. I know how to program, I've been doing it a long time. And yet learning a new codebase feels like learning a new language. And it doesn't help much in understanding the next new codebase. Maybe that's just how things have to be. I'd like to see if a better way is possible, if it's possible to learn faster by starting not with code but with scenarios that look like log files. "Welcome, newcomer. This is a text editor. Here's an edited sequence of events that happen when a key is pressed. Click on any line to locate it in the codebase, and to find some other scenarios that print it." Something like that, but easy enough for authors that such scenarios are actually created and kept updated. I have more details in a couple of the posts linked at the end: a) http://akkartik.name/post/wart-layers, and b) http://akkartik.name/post/tracing-tests. But yes, the article is a year old, and I hope to have something more concrete soon.