Disclaimer: I’m not quite sure who the audience is for this. I guess it’s describing a fun little project I put together, but it’s also written kind of like a tutorial, so you can maybe follow along. I don’t think it’s particularly beginner-friendly, though. Some knowledge of Java is assumed, but not much. The code is available on github.

Code coverage is a software metric that measures how much, and which parts, of the source code of a program were exercised in a given execution of that program. There are many different flavors of coverage data, for example tracking which lines or statements were executed, which functions were called, which branches or control flow paths were taken. In this post, we’ll walk through writing a simplistic coverage collection tool for Java.