Tag Archives: Max Kanat-Alexander

Code Health: Understanding Code In Review


This is another post in our Code Health series. A version of this post originally appeared in Google bathrooms worldwide as a Google Testing on the Toilet episode. You can download a printer-friendly version to display in your office.

By Max Kanat-Alexander


It's easy to assume that a developer who sends you some code for review is smarter than you'll ever be, and that's why you don't understand their code.

But in reality, if code is hard to understand, it's probably too complex. If you're familiar with the programming language being used, reading healthy code should be almost as easy as reading a book in your native language.

Pretend a developer sends you this block of Python to be reviewed:
def IsOkay(n):
f = False
for i in range(2, n):
if n % i == 0:
f = True
return not f

Don't spend more than a few seconds trying to understand it. Simply add a code review comment saying, "It's hard for me to understand this piece of code," or be more specific, and say, "Please use more descriptive names here."

The developer then clarifies the code and sends it to you for review again:
def IsPrime(n):
for divisor in range(2, n / 2):
if n % divisor == 0:
return False

return True

Now we can read it pretty easily, which is a benefit in itself.

Often, just asking a developer to clarify a piece of code will result in fundamental improvements. In this case, the developer noticed possible performance improvements since the code was easier to read—the function now returns earlier when the number isn't prime, and the loop only goes to n/2 instead of n.

However, now that we can easily understand this code, we can see many problems with it. For example, it has strange behavior with 0 and 1, and there are other problems, too. But most importantly, it is now apparent that this entire function should be removed and be replaced with a preexisting function for detecting if a number is prime. Clarifying the code helped both the developer and reviewer.

In summary, don't waste time reviewing code that is hard to understand, just ask for it to be clarified. In fact, such review comments are one of the most useful and important tools a code reviewer has!

Code Health: Google’s Internal Code Quality Efforts

By Max Kanat-Alexander, Tech Lead for Code Health and Author of Code Simplicity

There are many aspects of good coding practices that don't fall under the normal areas of testing and tooling that most Engineering Productivity groups focus on in the software industry. For example, having readable and maintainable code is about more than just writing good tests or having the right tools—it's about having code that can be easily understood and modified in the first place. But how do you make sure that engineers follow these practices while still allowing them the independence that they need to make sound engineering decisions?

Many years ago, a group of Googlers came together to work on this problem, and they called themselves the "Code Health" group. Why "Code Health"? Well, many of the other terms used for this in the industry—engineering productivity, best practices, coding standards, code quality—have connotations that could lead somebody to think we were working on something other than what we wanted to focus on. What we cared about was the processes and practices of software engineering in full—any aspect of how software was written that could influence the readability, maintainability, stability, or simplicity of code. We liked the analogy of having "healthy" code as covering all of these areas.

This is a field that many authors, theorists, and conference speakers touch on, but not an area that usually has dedicated resources within engineering organizations. Instead, in most software companies, these efforts are pushed by a few dedicated engineers in their extra time or led by the senior tech leads. However, every software engineer is actually involved in code health in some way. After all, we all write software, and most of us care deeply about doing it the "right way." So why not start a group that helps engineers with that "right way" of doing things?

This isn't to say that we are prescriptive about engineering practices at Google. We still let engineers make the decisions that are most sensible for their projects. What the Code Health group does is work on efforts that universally improve the lives of engineers and their ability to write products with shorter iteration time, decreased development effort, greater stability, and improved performance. Everybody appreciates their code getting easier to understand, their libraries getting simpler, etc. because we all know those things let us move faster and make better products.

But how do we accomplish all of this? Well, at Google, Code Health efforts come in many forms.

There is a Google-wide Code Health Group composed of 20%contributors who work to make engineering at Google better for everyone. The members of this group maintain internal documents on best practices and act as a sounding board for teams and individuals who wonder how best to improve practices in their area. Once in a while, for critical projects, members of the group get directly involved in refactoring code, improving libraries, or making changes to tools that promote code health.

For example, this central group maintains Google's code review guidelines, writes internal publications about best practices, organizes tech talks on productivity improvements, and generally fosters a culture of great software engineering at Google.

Some of the senior members of the Code Health group also advise engineering executives and internal leadership groups on how to improve engineering practices in their areas. It's not always clear how to implement effective code health practices in an area—some people have more experience than others making this happen broadly in teams, and so we offer our consulting and experience to help make simple code and great developer experiences a reality.

In addition to the central group, many products and teams at Google have their own Code Health group. These groups tend to work more closely on actual coding projects, such as addressing technical debt through refactoring, making tools that detect and prevent bad coding practices, creating automated code formatters, or making systems for automatically deleting unused code. Usually these groups coordinate and meet with the central Code Health group to make sure that we aren't duplicating efforts across the company and so that great new tools and systems can be shared with the rest of Google.

Throughout the years, Google's Code Health teams have had a major impact on the ability of engineers to develop great products quickly at Google. But code complexity isn't an issue that only affects Google—it affects everybody who writes software, from one person writing software on their own time to the largest engineering teams in the world. So in order to help out everybody, we're planning to release articles in the coming weeks and months that detail specific practices that we encourage internally—practices that can be applied everywhere to help your company, your codebase, your team, and you. Stay tuned here on the Google Testing Blog for more Code Health articles coming soon!