How to conduct code reviews (+ a checklist!)

how to conduct code reviews

GitLab’s recent DevSecOps global survey revealed that 60% of developers find code reviews “very valuable” for security and code quality. Respondents also noted that code reviews are a bottleneck, citing strictness, taking too long, finding someone to complete a review, and being unsure how to perform effective code reviews.

This post breaks down how to conduct code reviews efficiently and effectively, so developers can get the value out of them with fewer frustrations. You’ll learn:

  • 4 benefits of code reviews 
  • 5 best practices to consider
  • 4 tips to make your code reviews better 
  • 5 code review tools to explore 
  • A code review checklist starter pack to help you structure your process

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4 benefits of code reviews

Meaningful code reviews provide many benefits for programmers, development teams, and the product’s end-users. Below are four key benefits of creating a consistent code review practice.

1. Code reviews facilitate knowledge sharing.

Many programmers do their work in an isolated, independent environment. While deep work has benefits, resilient teams must share knowledge to withstand team changes, employee resignations, and unplanned time off (aka your bus factor). Code reviews promote cross-collaboration and encourage developers to interact, teach each other, and use team knowledge to uplevel individual skill sets. Decentralized knowledge can foster colleagues' trust rather than a “mine vs. yours” ownership mentality. 

2. Programmers can identify and address bugs sooner.

The sooner programmers identify and fix bugs, the cheaper it is to fix them. According to Deepsource, the relative cost to fix bugs increases 30x from the requirements phase to the production/post-release phase. Not only is it cheaper to address bugs sooner, but it’s also easier most of the time. The code is still fresh in developers’ minds, and issues may be less complex since the code is in an earlier stage. Addressing bugs produces better software in the long run and allows programmers to optimize code for better performance.

3. Reviews help maintain consistent coding styles.

Developers have unique programming styles, preferences, and specialized skills they bring to the table. Some level of individuality and uniqueness provides better solutions and creates teams who are better at problem-solving. But too much originality can hinder collaboration, stall progress, and create inconsistency in the results. You can use the code review process to ensure developers follow and maintain certain coding practices. This approach standardizes quality across team members and projects. It also helps current and future developers work together in the long run without wasting time trying to dissect the code to get on board.

4. Code reviews promote team cohesion. 

Similar to knowledge sharing, code reviews offer the opportunity to reduce working in silos while enabling teamwork and cross-collaboration. Benefits of teamwork in software development include improved code quality, enhanced creativity, elevated efficiencies, improved skills, enhanced business potential, and transparency. Code reviews are one tool you can implement and reap ongoing benefits from in the long term. 

5 code review best practices 

Not all code review strategies are successful. Structuring code reviews requires intention, thoughtful planning, and iteration to create the strategy that works best for your team. Below are five code review best practices to consider when implementing or revising your code review process:

1. Keep reviews manageable in size and length.

Effective peer code reviews aim for quantity over quality, which is why you should limit the number of lines of code (LOC) for review in one sitting. If you spend too much time reviewing code in one session or review too many lines of code, your review may be less effective and thorough (which defeats the purpose of a review). Our brains can only process so much information at once without losing interest or being able to give it our best efforts.

Smartbear conducted a study of a Cisco Systems programming team and found that developers should review no more than 200 to 4000 lines of code at one time. Beyond 400 LOC, developers’ ability to discover defects diminishes. 

Along the same lines, industry experts recommend being mindful of how much time you spend conducting a code review to yield the best results. Software developer Kathryn Hodge recommends spending no more than 60 to 90 minutes completing a code review. This falls in line with productivity research that suggests the most productive people work for approximately 52 minutes at a time, then take a break for 17 minutes. 

There are no hard-and-fast rules for structuring code reviews. What’s most important is finding a structure that works well for you and your teams and avoiding spending too much time and energy in exchange for poor results.

2. Compare code against standards, not personal preferences.

Don’t let code reviews become a platform for inserting nitpicky personal preferences in place of valuable feedback. The focus should be on meeting standards and preserving quality to get the most out of code reviews. To do this successfully, managers and organizations must supply developers with agreed-upon standards and perhaps a checklist to leverage during the review.

Managers and tenured developers should also teach new team members what they’re looking for in code reviews. For example, consider conducting team training encouraging developers to avoid getting nitpicky unless the changes negatively impact the code’s functionality. Emphasize your team’s coding standards so team members become familiar with them and know what they should keep an eye out for. In addition to standards, teams can use automated tools for quality and consistency.

One helpful suggestion for avoiding inserting personal preferences in a review is to ask the author if you can meet at a separate time for a knowledge share. This way, teammates can have healthy, conversational debates and share knowledge and best practices without stalling the current codebase. 

3. Provide constructive, concise, and actionable feedback.

Reviewers should provide neutral feedback and focus on improving the code. Additionally, reviewers should avoid judging the author and leaving vague comments. Constructive, concise, and actionable feedback will help the author of the code learn something new, make beneficial changes, and point them in the right direction rather than leave them guessing.

As a reviewer, consider the following when offering feedback:

Distinguish between required changes and suggestions in your feedback. 

Not all comments and remarks fall into the same category. It’s beneficial to call out what type of feedback you’re offering to ensure the author understands your expectations following the review. 

Explain the “why” in your remarks

Comments like, “This LOC is wrong and doesn’t make sense,” aren’t helpful or concise. The author receiving the feedback needs to know what about the LOC is incorrect, why it’s wrong, and what steps they can take to get back on track. Make it a point to explain why you’re leaving the comment that you are for learning opportunities, fewer follow-ups, and avoided frustrations. 

Provide actionable insights and learning lessons. 

Code reviews should help the code author learn how to do things differently and better next time. In your feedback, consider including additional reading resources when it makes sense. Provide links to pointers, lessons, and company documentation for reference. 

One final tip for building a constructive feedback code review culture: Teach developers to ask for specific feedback. “Be clear about what you want feedback on. When sending out a request for review, be specific. This will help focus the reviewer’s attention and ensure that they’re looking at the right things,” said Matt Post, programmer, and co-founder of WCAG Pros.

4. Rotate code reviewers.

Avoid falling into the trap of leveraging tenured developers as reviewers. Instead, involve everyone in the process. Carry the mindset that senior developers need to have their code reviewed just as much as entry-level developers. 

One way to implement a rotational process is to implement an automation tool to assign reviews. For example, on GitHub, users can leverage routing algorithms in which code reviews assignments automatically choose and assign reviewers through a round robin or load balance workload. 

5. Use a code review checklist to standardize the process.

Create a predetermined set of questions for team members to follow during the code review process for an added layer of consistency. A code review checklist adds a structured approach, so authors feel that their teammates are reviewing their work fairly across the board. Some categories to include in your code review checklist are readability, security, architecture, and reusability (and more on checklists later!)

4 tips for better code reviews

Spoiler alert: no code review is perfect. There are always areas for improvement and opportunities to deploy new tactics to test. Spice up your code review process with these four tips for doing code reviews better:

1. Incorporate a “what and why” review framework. 

Surface-level feedback and conducting code reviews to check a box aren’t valuable foundations for your code review process. If your development team currently provides feedback on what to change but isn’t explaining why the author should make a change, they’re missing an opportunity to grow their skills. 

A “what and why” review framework teaches teams how to suggest changes and explain their position, further enhancing their development knowledge and communication skills. Empower your team members to avoid accepting suggestions without understanding the reasoning behind them to build this explanatory nature into your coding culture.

2. Adjust code reviews in the context of the codebase.

Depending on the structure of your team and the nature of your work, consider tailoring code reviews. Specific, tailored reviews, particularly around the client’s asks, enables teams to provide better products to clients by double-checking that they’re meeting requirements. 

Take caution when implementing a tailored practice, especially if your team is low or short on resources, as this can require more time and effort. Conduct a standard review for quality and consistency purposes, and consider adding an additional checklist to take the review deeper if the codebase allows.

3. Teach team members how to be empathetic. 

Providing feedback can be harmful and unpleasant if you don’t execute the review process properly. Encourage team members to provide input, remove personal judgments, and remember that the author dedicated time and effort to writing their code. Organizations should prioritize creating psychologically safe environments with healthy working relationships for team members to engage in these activities meaningfully. Managers should also encourage positive remarks in addition to areas of opportunity for improvement to make the process as successful as possible.

4. Implement an open feedback loop.

Code reviews don’t need to be stagnant (however, when you find something that works well—leave it alone). Conduct post-review surveys with code authors and reviewers to improve your code reviews. On a recurring cadence such as quarterly, obtain feedback from all team members participating in code reviews. Be iterative and implement updates based on team feedback.

5 code review tools to try

Code review tools are a great resource to consider as part of the review process. If you aren’t sure where to start, here’s a list of five code review tools to get you started, listed in alphabetical order.

1. Azure Repos

Azure Repos is an Azure DevOps service enabling collaborative code reviews. With Azure Repos, you can perform more effective Git code reviews with threaded discussions, built-in continuous integration/continuous delivery (CI/CD) capabilities, and code quality mechanisms. 

Image source: Azure Repos - Microsoft 

2. Bitbucket 

Bitbucket’s code review process supports team collaboration, enables teams to find bugs faster, and allows them to merge confidently. With a one-page view, developers reduce context switching and can focus on improving the code.

Image source: Bitbucket - Atlassian 

3. Collaborator 

Smartbear’s Collaborator tool offers comprehensive review capabilities, proof of review with electronic signatures, integrations with other major development tools like GitHub and GitLab, and real-time threaded conversations. 

Image source: Smartbear

4. GitHub

GitHub built lightweight code review tools into their pull requests. Team members can see every update, discuss code in comments and reviews, resolve conflicts, and merge the highest quality code. 

Image source: GitHub

5. GitLab

GitLab’s code review process streamlines code review and approvals by centralizing the review and approval workflows. Noteworthy features include file attachments (so you can communicate beyond text), threaded discussions, bulk edit merge requests, custom notifications, approval rules, and more. 

Image source: GitLab

Code review checklist starter pack

For effective code reviews, you’ll want to tailor your checklist and validate that it’s relevant to your teams and specific products. Below is a code review checklist starter pack, including some examples of recommended questions to help you create your own.

  • Does this code change do what the author intended it to?
  • Can we simplify this solution?
  • Is the code scalable?
  • Is the code easy to test?
  • Will any events or inputs break the code if we implement the change?
  • Does the code change meet our agreed-upon team/organization standards?
  • Did the author update the appropriate documentation?
  • Is there any risk of this code change negatively impacting performance?
  • Is the code easy to understand?
  • Will this code change impact other teams, and should they also review the change?

Here’s to better code

The code review process is great for sharing knowledge, fixing bugs, and ensuring consistent code quality. Code reviews should be manageable, constructive, and involve all developers as the author and reviewer. Specific feedback, contextual adjustments, encouraging empathy, and responding to developer feedback on the process can help improve your code reviews. Consider using a code review tool and a standardized checklist to streamline your process. Happy coding!

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