How Google Tests Software - Part One

How Google Tests Software - Part One

By James Whittaker

This is the first in a series of posts on this topic.

The one question I get more than any other is "How does Google test?" It's been explained in bits and pieces on this blog but the explanation is due an update. The Google testing strategy has never changed but the tactical ways we execute it has evolved as the company has evolved. We're now a search, apps, ads, mobile, operating system, and so on and so forth company. Each of these Focus Areas (as we call them) have to do things that make sense for their problem domain. As we add new FAs and grow the existing ones, our testing has to expand and improve. What I am documenting in this series of posts is a combination of what we are doing today and the direction we are trending toward in the foreseeable future.

Let's begin with organizational structure and it's one that might surprise you. There isn't an actual testing organization at Google. Test exists within a Focus Area called Engineering Productivity. Eng Prod owns any number of horizontal and vertical engineering disciplines, Test is the biggest. In a nutshell, Eng Prod is made of:

1. A product team that produces internal and open source productivity tools that are consumed by all walks of engineers across the company. We build and maintain code analyzers, IDEs, test case management systems, automated testing tools, build systems, source control systems, code review schedulers, bug databases... The idea is to make the tools that make engineers more productive. Tools are a very large part of the strategic goal of prevention over detection.

2. A services team that provides expertise to Google product teams on a wide array of topics including tools, documentation, testing, release management, training and so forth. Our expertise covers reliability, security, internationalization, etc., as well as product-specific functional issues that Google product teams might face. Every other FA has access to Eng Prod expertise.

3. Embedded engineers that are effectively loaned out to Google product teams on an as-needed basis. Some of these engineers might sit with the same product teams for years, others cycle through teams wherever they are needed most. Google encourages all its engineers to change product teams often to stay fresh, engaged and objective. Testers are no different but the cadence of changing teams is left to the individual. I have testers on Chrome that have been there for several years and others who join for 18 months and cycle off. Keeping a healthy balance between product knowledge and fresh eyes is something a test manager has to pay close attention to.

So this means that testers report to Eng Prod managers but identify themselves with a product team, like Search, Gmail or Chrome. Organizationally they are part of both teams. They sit with the product teams, participate in their planning, go to lunch with them, share in ship bonuses and get treated like full members of the team. The benefit of the separate reporting structure is that it provides a forum for testers to share information. Good testing ideas migrate easily within Eng Prod giving all testers, no matter their product ties, access to the best technology within the company.

This separation of project and reporting structures has its challenges. By far the biggest is that testers are an external resource. Product teams can't place too big a bet on them and must keep their quality house in order. Yes, that's right: at Google it's the product teams that own quality, not testers. Every developer is expected to do their own testing. The job of the tester is to make sure they have the automation infrastructure and enabling processes that support this self reliance. Testers enable developers to test.

What I like about this strategy is that it puts developers and testers on equal footing. It makes us true partners in quality and puts the biggest quality burden where it belongs: on the developers who are responsible for getting the product right. Another side effect is that it allows us a many-to-one dev-to-test ratio. Developers outnumber testers. The better they are at testing the more they outnumber us. Product teams should be proud of a high ratio!

Ok, now we're all friends here right? You see the hole in this strategy I am sure. It's big enough to drive a bug through. Developers can't test! Well, who am I to deny that? No amount of corporate kool-aid could get me to deny it, especially coming off my GTAC talk last year where I pretty much made a game of developer vs. tester (spoiler alert: the tester wins).

Google's answer is to split the role. We solve this problem by having two types of testing roles at Google to solve two very different testing problems. In my next post, I'll talk about these roles and how we split the testing problem into two parts.