How often have we heard those words? Or used them ourselves?

“Oh this is just a simple change, it won’t break a thing.” And then all hell breaks lose.

Yet, we also hear the reverse at times. “This is pretty complex, I’ll be surprised if it works the first time, or if it doesn’t break something.” And yet then nothing bad seems to happen.

We may observe this, but we don’t necessarily stop to think about the why. I’ve seen this happen a lot in IT, but honestly, I’ve seen this happen elsewhere and often when we read about accidents in areas such as caving, this also holds true.

I argue that in this case the perception is often true. Let me put in one caveat. There’s definitely a bias in our memory where we don’t recall all the times where simple things don’t break things, but the times it does, it really stands out.

The truth is, whenever we deal with complex systems, even simple changes aren’t so simple. But we assume they are and then are surprised when they have side effects. “Oh updating that path here won’t break anything. I only call it one place, and I’ll update that.” And you’re good. But what you didn’t realize was another developer liked your script, so made a copy and is using it for their own purposes and now their code breaks because of the new path. So your simple change isn’t so simple.

Contrast that to the complex change. I’m in the middle up refactoring a stored procedure. It’s complex. I suspect it’ll break something in production. But, honestly, it probably won’t. Not because I’m am awesome T-SQL developer, but, because of our paranoia, we’ll be testing this in UAT quite a bit. In other words, our paranoia drives our testing to a higher level.

I think it behooves us to treat even simple changes with more respect than we do and test them.

In the world of caving we use something called SRT – Single Rope Technique. This is the method we use for ascending and descending a rope. When ascending, if you put your gear on wrong at the bottom, generally there’s no real risk other than possible embarrassment. After all, you’re standing on the ground. But obviously a the top, it’s critical to put your equipment on correctly, lest your first step be your last. Similarly, we practice something known as a change-over; changing from ascending to descending, or descending to ascending while on rope. When changing from climbing to descending you want to make sure you do it correctly lest you find yourself descending at 9.8m/s^2. To prevent accidents, we ingrain in students “load and test your descent device before removing your other attachment point.” Basically, while you’re still secured to something at the top, or to your ascending devices if you’re partway up the rope, put your entire weight on your descent device and lower yourself 1-2″. If you succeed, great, then you can detach yourself from whatever you are attached to at the top, or remove your ascending devices. If somehow you’ve screwed something up and the descent device comes off the top or otherwise fails, you’ve got a backup.

Now, I will interject, getting on rope at the top of a pit, or a changeover is something an experienced caver will have done possibly 100s if not 1000s of times. It’s “a simple change”. Yet we still do the test because a single failure can be fatal. And I have in fact seen a person fail to properly test their descent device. And moreover, this wasn’t in a cave, or other dark or cramped space. It was in broad daylight on the edge of the RPI Student Union! This was about as simple as it could get! Fortunately he heard it start to fail and grabbed the concrete railing for dear life. In this particular case a failure most likely would not have been fatal, but would have caused serious injury.

So, despite having gotten on rope 100s of times myself, I ALWAYS test. It’s a simple change. But the test is also simple and there’s no reason to skip it.

The morale of the story, even your simple changes should be tested, lest you find they’re not so simple, or their failures aren’t so minor.