Lines of code vs. Lines of test

My last project was a rescue mission. A 20k line rails app with only about 34% line coverage from the tests. No wonder the previous team had failed. 5 months later we made a successful rescue, and were up to about 71% line coverage. Watching those stats go from totally-screwed to mostly-un-screwed felt good. Metric_fu provided all the cool and useful graphs for that project: rcov, flog, reek, etc. One graph that was missing was lines of code vs. lines of test. I was sure that graph would have made a big beautiful X marks the spot, because LOC had steadily gone down and LOT had steadily risen. The moment those lines crossed would have been a great opportunity for toasting the health of the codebase.

Well, good news for those of you looking for excuses to toast your codebase. The brand spanking new Metric_fu 1.4 features a froody new LOC vs LOT graph.

I've been using it on my new project. This codebase is healthy, so no X marks the spot action here, but it is still interesting. From our graph it looks like things started out with 2 lines of test for every line of code, and have been working their way towards 3 lines of test for every line of code. (Our rcov % has stayed about 98% the whole time.) Does that mean that as the codebase increases you have to have an increasing ratio of tests to code? Given a sampling of 2 projects I can't really make any useful generalizations. But what I can do is recommend metric_fu to everyone. Graphs are a great way to start talking about how to improve your codebase and your process, and metric_fu makes it easy to get started. And remember, always use your Vanna White hands when you are exhibiting your graphs to your team mates. If it can make a game-show as lame as Wheel of Fortune successful, then it may work for you.