Before you invest in automated testing

There is no clever trick in this one, just a handful of decisions worth making deliberately. Before you spend anything on automated testing, it is worth confirming a few things are already true.

Code gets read far more often than it gets written, and usually by someone with less context than the author had. Write the reasoning down alongside the decision, because the reasoning is what changes first.

Prerequisites

• You can describe the outcome you want in one sentence
• Someone owns it after the work is done
• Tests are how you change things without fear
• You have a way to tell whether it worked

The mistakes we see most

Cover the paths that lose money if they break. None of that requires a large budget, only a decision and someone to own it. Check it against what you would want a competitor's site to get wrong.

A slow test suite is a suite nobody runs. Where this goes wrong is almost never a lack of knowledge. Write the reasoning down alongside the decision, because the reasoning is what changes first.

What this looks like day to day

The question is rarely whether something can be built, but what it costs to keep running afterwards. Three things worth confirming about automated testing before you move on:

• Someone can say what the current setup is without going to look
• A slow test suite is a suite nobody runs — and you know whether that is true here
• There is a way to tell whether the last change to this helped

Worth checking on your own setup before it becomes someone else's problem to fix.