Code Health: To Comment or Not to Comment?

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 Dori Reuveni and Kevin Bourrillion

While reading code, often there is nothing more helpful than a well-placed comment. However, comments are not always good. Sometimes the need for a comment can be a sign that the code should be refactored.

Use a comment when it is infeasible to make your code self-explanatory. If you think you need a comment to explain what a piece of code does, first try one of the following:

  • Introduce an explaining variable.
    // Subtract discount from price.
    finalPrice = (numItems * itemPrice)
    - min(5, numItems) * itemPrice * 0.1;
    price = numItems * itemPrice;
    discount =
    min(5, numItems) * itemPrice * 0.1;
    finalPrice = price - discount;

  • Extract a method.
    // Filter offensive words.
    for (String word : words) { ... }
    filterOffensiveWords(words);

  • Use a more descriptive identifier name.
    int width = ...; // Width in pixels.
    int widthInPixels = ...;

  • Add a check in case your code has assumptions.
    // Safe since height is always > 0.
    return width / height;
    checkArgument(height > 0);
    return width / height;

There are cases where a comment can be helpful:

  • Reveal your intent: explain why the code does something (as opposed to what it does).
    // Compute once because it’s expensive.

  • Protect a well-meaning future editor from mistakenly “fixing” your code.
    // Create a new Foo instance because Foo is not thread-safe.

  • Clarification: a question that came up during code review or that readers of the code might have.
    // Note that order matters because...

  • Explain your rationale for what looks like a bad software engineering practice.
    @SuppressWarnings("unchecked") // The cast is safe because...

On the other hand, avoid comments that just repeat what the code does. These are just noise:

// Get all users.
userService.getAllUsers();
// Check if the name is empty.
if (name.isEmpty()) { ... }

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Evolution of GTAC and Engineering Productivity

When Google first hosted GTAC in 2006, we didn’t know what to expect. We kicked off this conference with the intention to share our innovation in test automation, learn from others in the industry and connect with academia. Over the last decade we’ve had great participation and had the privilege to host GTAC in North America, Europe and Asia — largely thanks to the many of you who spoke, participated and connected!


In the recent months, we’ve been taking a hard look at the discipline of Engineering Productivity as a logical next step in the evolution of test automation. In that same vein, we’re going to rethink what an Engineering Productivity focused conference should look like today.  As we pivot, we will be extending these changes to GTAC and because we expect changes in theme, content and format, we are canceling the upcoming event scheduled in London this November. We’ll be bringing the event back in 2018 with a fresh outlook and strategy.


While we know this may be disappointing for many of the folks who were looking forward to GTAC, we’re excited to come back with a new format which will serve this conference well in today’s environment.

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Code Health: Too Many Comments on Your Code Reviews?

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 Tom O’Neill

Code reviews can slow down an individual code change, but they’re also an opportunity to improve your code and learn from another intelligent, experienced engineer. How can you get the most out of them?
Aim to get most of your changes approved in the first round of review, with only minor comments. If your code reviews frequently require multiple rounds of comments, these tips can save you time.


Spend your reviewers’ time wisely—it’s a limited resource. If they’re catching issues that you could easily have caught yourself, you’re lowering the overall productivity of your team.
Before you send out the code review:
  • Re-evaluate your code: Don’t just send the review out as soon as the tests pass. Step back and try to rethink the whole thing—can the design be cleaned up? Especially if it’s late in the day, see if a better approach occurs to you the next morning. Although this step might slow down an individual code change, it will result long-term in greater average throughput.
  • Consider an informal design discussion: If there’s something you’re not sure about, pair program, talk face-to-face, or send an early diff and ask for a “pre-review” of the overall design.
  • Self-review the change: Try to look at the code as critically as possible from the standpoint of someone who doesn’t know anything about it. Your code review tool can give you a radically different view of your code than the IDE. This can easily save you a round trip.
  • Make the diff easy to understand: Multiple changes at once make the code harder to review. When you self-review, look for simple changes that reduce the size of the diff. For example, save significant refactoring or formatting changes for another code review.
  • Don’t hide important info in the submit message: Put it in the code as well. Someone reading the code later is unlikely to look at the submit message.
When you’re addressing code review comments:
  • Re-evaluate your code after addressing non-trivial comments: Take a step back and really look at the code with fresh eyes. Once you’ve made one set of changes, you can often find additional improvements that are enabled or suggested by those changes. Just as with any refactoring, it may take several steps to reach the best design.
  • Understand why the reviewer made each comment: If you don’t understand the reasoning behind a comment, don’t just make the change—seek out the reviewer and learn something new.
  • Answer the reviewer’s questions in the code: Don’t just reply—make the code easier to understand (e.g., improve a variable name, change a boolean to an enum) or add a comment. Someone else is going to have the same question later on.

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GTAC Diversity Scholarship

by Lesley Katzen on behalf of the GTAC Diversity Committee

We are committed to increasing diversity at GTAC, and we believe the best way to do that is by making sure we have a diverse set of applicants to speak and attend. As part of that commitment, we are excited to announce that we will be offering travel scholarships again this year.
Travel scholarships will be available for selected applicants from traditionally underrepresented groups in technology.

To be eligible for a grant to attend GTAC, applicants must:

  • Be 18 years of age or older.
  • Be from a traditionally underrepresented group in technology.
  • Work or study in Computer Science, Computer Engineering, Information Technology, or a technical field related to software testing.
  • Be able to attend core dates of GTAC, November 14th – 15th 2017 in London, England.

To apply:
You must fill out the following scholarship formand register for GTAC to be considered for a travel scholarship.
The deadline for submission is July 1st. Scholarship recipients will be announced on August 15th. If you are selected, we will contact you with information on how to proceed with booking travel.

What the scholarship covers:
Google will pay for round-trip standard coach class airfare to London for selected scholarship recipients, and 3 nights of accommodations in a hotel near the Google King’s Cross campus. Breakfast and lunch will be provided for GTAC attendees and speakers on both days of the conference. We will also provide a £75.00 gift card for other incidentals such as airport transportation or meals. You will need to provide your own credit card to cover any hotel incidentals.

Google is dedicated to providing a harassment-free and inclusive conference experience for everyone. Our anti-harassment policy can be found at:
https://www.google.com/events/policy/anti-harassmentpolicy.html

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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!

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