July 28, 2014
by Dan Poirier
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Categories:
Technical
Culture

A Culture of Code Reviews

Code reviews are one of those things that everyone agrees are worthwhile, but sometimes don’t get done. A good way to keep getting the benefits of code reviews is to establish, and even nurture, a culture of code reviews.

When code reviews are part of the culture, people don’t just expect their changes to be reviewed, they want their changes reviewed.

Some advantages of code reviews

We can all agree that code reviews improve code quality by spotting bugs. But there are other advantages, especially when changes are reviewed consistently.

Having your own code reviewed is a learning experience. We all have different training and experiences, and code reviews give us a chance to share what we know with others on the team. The more experienced developer might be pointing out some pitfall they’ve learned by bitter experience, while the enthusiastic new developer is suggesting the latest library that can do half the work for you.

Reviewing other people’s code is a learning experience too. You’ll see better ways of doing things that you’ll want to adopt.

If all code is reviewed, there are no parts of the code that only one person is familiar with. The code becomes a collaborative product of the team, not a bunch of pieces “owned” by individual programmers.

Obstacles to code reviews

But you only get the benefits of code reviews if you do them. What are some things that can get in the way?

Insufficient staffing is an obvious problem, whether there’s only one person working on the code, or no one working on the code has time to review other changes, or to wait for their own to be reviewed. To nurture a culture of code reviews, enough staff needs to be allocated to projects to allow code reviews to be a part of the normal process. That means at least two people on a team who are familiar enough with the project to do reviews. If there’s not enough work for two full-team team members, one member could be part-time, or even both. Better two people working on a project part-time than one person full-time.

Poor tools can inhibit code reviews. The more difficult something is, the more likely we are to avoid doing it. Take the time to adopt a good set of tools, whether GitHub’s pull requests, the open source ReviewBoard project, or anything else that handles most of the tedious parts of a code review for you. It should be easy to give feedback, linked to the relevant changes, and to respond to the feedback.

Ego is one of the biggest obstacles. No one likes having their work criticized. But we can do things in ways that reduce people’s concerns.

Code reviews should be universal - everyone’s changes are reviewed, always. Any exception can be viewed, if someone is inclined that way, as an indication that some developers are “better” than others.

Reviews are about the code, not the coder. Feedback should be worded accordingly. Instead of saying “You forgot to check the validity of this input”, reviewers can say “This function is missing validation of this input”, and so forth.

We do reviews because our work is important and we want it to be as good as possible, not because we expect our co-workers to screw it up. At the same time, we recognize that we are all human, and humans are fallible.

Establishing a culture of code reviews

Having a culture where code reviews are just a normal part of the workflow, and we’d feel naked without them, is the ideal. But if you’re not there yet, how can you move in that direction?

It starts with commitment from management. Provide the proper tools, give projects enough staffing so there’s time for reviews, and make it clear that all changes are expected to be reviewed. Maybe provide some resources for training.

Then, get out of the way. Management should not be involved in the actual process of code reviews. If developers are reluctant to have other developers review their changes, they’re positively repelled by the idea of non-developers doing it. Keep the actual process something that happens among peers.

When adding code reviews to your workflow, there are some choices to make, and I think some approaches work better than others.

First, every change is reviewed. If developers pick and choose which changes are reviewed, inevitably someone will feel singled out, or a serious bug will slip by in a “trivial” change that didn’t seem to merit a review.

Second, review changes before they’re merged or accepted. A “merge then review” process can result in everyone assuming someone else will review the change, and nobody actually doing it. By requiring a review and signoff before the change is merged, the one who made the change is motivated to seek out a reviewer and get the review done.

Third, reviews are done by peers, by people who are also active coders. Writing and reviewing code is a collaboration among a team. Everyone reviews and has their own changes reviewed. It’s not a process of a developer submitting a proposed change to someone outside the team for approval.

The target

How will you know when you’re moving toward a culture of code reviews? When people want their code to be reviewed. When they complain about obstacles making it more difficult to get their code reviewed. When the team is happier because they’re producing better code and learning to be better developers.

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