What Does “Shift Left” Mean?

Posted by Load Impact on Jan 8, 2018

The phrase “shift left” testing has gained some recent traction. But what does “shift left” mean for you? In short, it means what you already know: the earlier you test, the better, and you should test consistently and continuously.

It’s not a new concept, by any means. The concept of shifting left is simple: you’re moving testing to earlier stages of your development process. Since that process is often diagrammed left-to-right, shifting left implies shifting testing earlier in the process. (Here’s a decent overview of “shift left testing” models with links to explore more.)

With nearly every process that involves building something, finding errors earlier in the process solves a magnitude of problems were those errors to be discovered later in the process. “Shift left testing” means you’re catching errors upstream before they have a chance to multiply and cost time and effort.

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Don’t get caught up in the “shift left” buzzword, however. It means doing what you instinctively know to do. It means doing what we believe should be done: putting load testing in the hands of the developers, and doing that testing as early in the process as possible.

We believe in putting developers first. That’s why all the Load Impact products are designed for developers, and why we emphasize load testing that’s both consistent and continuous. When load testing is part of the development process, development is easier and better.

You may have already “shifted left” your unit testing and functional testing, in other words, you’ve pushed both of those earlier in the development process. Because the nature of development has changed from periodic builds to continuous delivery, testing has become continuous as well.

Given all of these trends, load testing should be continuous and consistent as well. As you’ve heard us suggest before, continuous load testing implies that your load tests should be part of your regular build cycle. If you’re producing daily builds, run at least basic load tests along with those builds.

The insights you gain when you catch site performance changes as soon as they happen can prevent minor issues from becoming major ones. The same principle applies with any kind of testing done earlier in the development process: catch errors early and thereby minimize their effects. The “shift left,” in addition, implies that where a large development organization might have reserved testing until a release candidate reached a dedicated testing team late in the process, testing is now done earlier and throughout the process.

Remember, too, that load testing should be not only continuous but consistent. It’s easy to let performance testing wait, or procrastinate it until an anticipated traffic peak. But doing so means that your continuous testing has less benefit, and problems aren’t caught early enough. Consistent application of continuous testing is essential.

So, when you hear “shift left testing,” remember: it just means you, as a developer, get consistent feedback from continuous load testing, and build better apps, sites and code.

Topics: DevOps, automated testing, Load Testing, Continuous Load Test, consistent testing, shift left

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