What Is Code Review? The Purpose and Steps Behind an Effective Code Review Process

Co-authored by Hannah Madden

Last Updated: September 24, 2021 References

If you work in the programming world, you may have heard of the code review process. While not every development team uses this process, it can be a helpful tool when merging codes together or debugging before a big debut. In this article, we’ve answered your common questions about the code review process so you can decide if you’d like to use it in the future.

Question 1

Question 1 of 6:
What is the purpose of a code review?

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It exposes bugs and ensures quality of the code. Bugs in your code are going to happen—it’s just a fact of life. During the code review process, someone will come in and expose those bugs to ensure they can be fixed before they make it to production. They can also do a quality control check to make sure the code is up to standards.^{[1]
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It creates a collaborative environment. Code reviews often encourage peers to talk to each other, especially if they’re on different teams. Debuggers and programmers can work together to fix the code and work out any issues before the code gets published.^{[2]
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It teaches debugging skills to members of the team. Debugging is an important skill for all coders to learn. Someone might be great at writing code, but not so good at debugging it. If that’s the case, they can learn these skills by getting feedback and working on their code so it runs smoothly.^{[3]
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Question 2

Question 2 of 6:
What are the steps in the code review process?

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Assign a reviewer for the code. Usually, a code review will happen when 2 codes need to merge. In that case, the reviewer will usually be a person from the other team who has worked on the code that you’ll be merging with. The reviewer can be anyone from that team, as long as they know how to spot bugs and errors in a code.^{[4]
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- The person who wrote the code is called the author.
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Have the reviewer add their comments, then send the code back. The reviewer doesn’t make any changes to the code, they just review it. They can add comments about bugs or things that won’t merge well for the author to look at. Then, the author can figure out how to implement those changes to improve the code.^{[5]
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Make changes to the code until it’s approved by the reviewer. When merging codes together, most teams implement a pull review process. The author can make changes to the code and have it reviewed as many times as they want. When the reviewer feels like the code will merge smoothly, they can approve the pull review process and accept the code.^{[6]
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Question 3

Question 3 of 6:
What is a code review document?

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It’s the document that contains all of the reviewer’s notes. This isn’t a standardized document, so it can be formatted in a way that’s most helpful to you and your team. This document will be shared with the author of the code so they can check out what the reviewer is saying. It’s easiest to create this document on a shared platform, like Google Docs, so multiple team members can view it at once.^{[7]
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- If you’re creating a code review document, include things like bugs, errors, or discrepancies that need to be addressed before you can approve the code.

Question 4

Question 4 of 6:
What is the best code review tool?

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Gerrit is an open source code review tool from Google. All you need to do is download it onto your browser and upload your code. Then, members of the Gerrit community will review your code and leave comments on how you could improve it. You can choose which changes to implement and which ones to ignore when you edit your code.^{[8]
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- To download Gerrit, visit https://www.gerritcodereview.com/.
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PullRequest is a code review tool by GitHub. GitHub is one of the most well-known open source web hosting service on the internet. If you already use GitHub, you can sign up for PullRequest to access code reviews from the community. Just like other code review processes, you can choose whether or not you want to implement any of the changes that are recommended.^{[9]
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- To sign up for PullRequest, visit https://www.pullrequest.com/.
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Question 5

Question 5 of 6:
How many types of code review techniques are there?

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Instant code review. This type of review happens while one programmer is programming and the other is reviewing the code as it’s written. Changes can be made instantly, and the code is reviewed and checked for quality before it’s finalized.^{[10]
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Synchronous code review, or over the shoulder review. This type of review happens when the reviewer stands over the author's shoulder and gives their comments out loud. It’s the most common and the most informal type of review, but it happens quickly and changes can be implemented almost immediately.^{[11]
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Asynchronous code review. This review happens after the code is complete. The author will send the code to the reviewer, then move onto their next task. The reviewer will then make their comments and send the code back to the author so they can make changes.^{[12]
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Code review once in a while. This is the least common type of code review, because it’s mostly about teaching the code review process. Once a month, sit down with your team and present a code for everyone to review. All the developers will throw out their thoughts and ideas, and changes can be made instantly in a group setting.^{[13]
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Question 6

Question 6 of 6:
How do I prepare to review code?

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Remember that you’re reviewing code, not the author. Keep your comments civil, and don’t berate anyone for making mistakes. You’re here to point out things in the code that could be better, not tear down the author for doing something you wouldn’t do.^{[14]
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See code review as a collaborative effort. When you review someone’s code, you’re working with them to make the code better as a team. Feel free to chat with the author, get clarification, or ask them questions about their code if you’re confused.^{[15]
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