Nelson's log

Testing discipline

One of my successes in my professional career has been advocating for unit testing. I helped lead the charge for automated unit test suites inside Google, particularly for our Java code, and that ended up being hugely useful.

I’m nowhere near as disciplined when I’m working alone on my little hacks. It’s still just too much effort to write tests! It feels like twice the work. For a long lived software project with many users, sure, it’s worth the investment. But a one-off hack you’re not going to ever pick up again? Is it even worth the bother of remembering Python’s baroque unittest syntax to set up a test framework? (I have to look that up every… single… time…)

But small hacks have a way of becoming bigger things, vital projects. I’m continuing to work on my Slack / League of Legends integration. I may even get a bunch of new users, I found a community of a few hundred people who could use it! Yay! But I’ve gotten to a point of paralysis where I was afraid to make changes because I couldn’t tell if I would break things other than pushing it to the live system and then see if cron mailed me any errors. Derp.

Unfortunately this project is particularly thorny to test. I’m integrating with two different online APIs (Riot and Slack). I’m also storing data in a database, and I’ve still never seen a good solution for mocking out a stateful database. For now I’m just going with ugly hacks. I’ve put wrappers around the Riot API calls that will load canned data from a pickle, a sort of persistent memoization. And I’m just accepting the test script needs to create a fresh test database and populate it from scratch. That’s not the ideal of unit tests, but it is still some form of useful automated testing.

I already feel relief and confidence from having even something very basic in place. Now I can type “./” before deploying and at least know if the scripts are going to blow up on some really stupid error. And I have a place now to add more sophisticated tests for correctness.

Update boy what a difference that simple test suite has made. I’ve felt free to make way more aggressive changes to my code now. Without fear.