fragile (code) - handle with care

shards CC BY 2.0
by zappowbang

I'm working on a "legacy" software system. Legacy means different things; in this case I mean it has been around for a few years. The original developers are long gone, and there are numerous sections which are a mystery. Even more annoying, the code produces mystery entries in the database. There are columns with fields that have dual, hidden meanings. There are extra rows for undocumented special cases.

One of my colleagues, let's call him "Mr Eager-Beaver," recently decided he'd had enough, and removed some lines of code which had been adding apparently extraneous information into the database. He's not an idiot, so he tried doing this on a test system first, and found that nothing went wrong. So he argued for committing the change, and so it was.

Unfortunately, the application is extremely large and complex. Being finite, I'm sure you could design a suite of tests which check every possible feature in the application. However, the company motto is "we will test no code before its time." The end result is that we actually have a very limited suite of tests for this application. Further, from a QA perspective, you can't just go in and hit a few pages, click a few buttons, and declare a code change has done no damage.

So ever since this change was committed, we've been uncovering bugs related to it. In a few dusty corners of source code, the application expects to find the missing information in the database, but doesn't, and barfs.

It wouldn't be so bad if these bugs were easy to find, or if they could all be dumped on the original hero who did the refactoring. No; what happens is that you have no idea what is causing the bug until, after several hours of research, the realization dawns on you: "Oh, this is due to Eager-Beaver's code change!" At that point, you can fix the thing pretty easily, and there's no point in reassigning the bug to him.

So far I have had two such bugs assigned to me. Eager is actually a pretty decent guy, so while I do get an urge to come over and give him a good metaphysical ass-kicking when I finally discover the source of the bug, I don't. I can only hope he's been assigned his own fair share of these bugs. And that he'll be as nice to me, whenever he uncovers some code crime of my own.