Testing as prevention instead of diagnosis

On the topic of testing clichés, I recently heard again something along the lines of “testing only provides information, it doesn’t increase quality by itself.” There was a time where I might have agreed with that, but lately I’m not so sure.

The idea is that testing alone can’t make the product any better, because in order to make the product better, someone actually has to act on the information that testing provides. That step, the model goes, is a step outside the “testing” umbrella. Somebody decides to make a change, and it’s that change that improves the quality of the product.

It’s the kind of sentiment that’s perhaps technically true, but in an unsatisfyingly narrow sense. It undersells what testing does, and also feels somewhat dated in a world with agile whole-team testing and Modern Testing. Positioning testing as information gathering is much like saying the product is a patient and testing is the diagnosis. Running tests and getting a diagnosis doesn’t cure a person of a bug any more than it cures a product of one. This formulation, though, makes it easy to think of testing as just one phase or step towards improving quality. As a discipline we’ve moved beyond that.

Of course the change that improved the quality of the product wouldn’t have happened without the information that testing surfaced, but it’s more than that. If testing isn’t silo’d (and it shouldn’t be), then the practice of testing can actually change the way developers think about what they’re doing. We know that talking about testing ideas early in the process prevents bugs before they’re written. The presence of testing as a practice, and the recognition of it as an activity that anybody can and should take part in instead of a singular role, makes the team better able to deliver quality.

Testing is not just about providing information. Yes, that diagnosis element is part of it—we still have to run tests and get information—but only part. My mindset now is much more aligned with the idea that testing is about enabling the team to build a better product. Testing as prevention. This does make the product healthier.