A code review is when someone other than an author inspects source code and looks for issues. Whether you have to give code reviews or sit on the receiving end, you’ve seen the latencies they can add to your workflow. Thankfully, a great code review checklist can speed up the process and increase the thoroughness of code reviews.
Following code review best practices can benefit your business and the final product. Whether your reviews rely on multiple people, automation, or asynchronous feedback, our guide covers how you can be a better code reviewer. To go the extra mile, we’ll share resources every developer should have, including our code review checklist template.
Table of contents:
A comprehensive code review checklist
Senior developers follow several code review guidelines when studying someone’s work. They have to consider the code’s design, style, functionality, complexity, naming, and testing. There’s a lot of moving pieces to a thorough code review, that’s why it’s so important that code reviewers take a structured and meticulous approach. Leveraging our seven-step checklist will ensure nothing gets missed.
1. Verify feature requirements
Every review starts with a basic question: “Does this code accomplish what the end user needs?” Devs working on a project aren’t coding in a vacuum. Their program needs to reliably perform functions the user expects. If your developer missed this step, postpone the review until the code offers the full range of features.
To check the feature requirements, ask yourself:
Is there any missing functionality?
Are there any poorly implemented functions?
Could they add any related functions the user would like?
2. Assess readability
Even if the code does what’s advertised, you aren’t out of the woods yet. Beyond meeting basic requirements, you want easy-to-understand, clean code.
Review the legibility by asking:
Can you easily identify the code block starting and ending point?
Can the lines fit on a standard laptop screen (14 inches) or desktop screen (22-24 inches)?
Does the code speak for itself and convey its purpose?
Does it prioritize clarity and brevity?
Does it avoid obscure language?
Can you discern the role of specific functions, methods, or classes?
Did the dev break the code into easy-to-understand chunks?
3. Test maintainability
Over time, you may have to expand or change your code, so ensuring it’s easy to maintain and adjust will save you a few headaches.
Ask yourself these questions to assess maintainability:
Is the code easy to test and debug?
Can you configure the code to quickly change data values?
Is the code tied to another system or an outdated program?
Does the code rely on functions or technology you want to phase out?
4. Check for security vulnerabilities
Perfectly functional code can still present vulnerabilities your dev was too busy to notice. While a sleep-deprived programmer might miss some security risks, code reviewers can’t risk someone exploiting their code.
To avoid security vulnerabilities, ask these questions:
Does the code use outdated tools or ones with known security problems?
If you wanted to steal data or access a system, do you see vulnerabilities?
Does the code leverage authentication and authorization for security?
Is the user’s input sanitized to prevent security attacks?
Does the code securely store user data?
Does the code protect P2 or other GDPR-related data?
5. Consider speed and performance
Your problems don’t end with security; the user still expects reliable performance. Code reviewers also need to weigh a program’s resource consumption against its speed. Balancing these priorities isn’t always easy, but great code should check off both boxes.
Ask yourself a few questions to assess speed and performance:
Does the code contain inefficient string concatenations, logging, or allocations of objects?
Can you see duplicate code you don’t need?
Will the program negatively affect system performance overall?
Does the code rely on poorly optimized assets or multiple API requests?
6. Confirm adequate documentation
The best documentation explains what a codebase does and how you can use it. However, even great code may need some external documentation for ease of use.
To make sure documentation is up to snuff, ask:
Does the documentation explain the code’s purpose?
Does the documentation teach the user how to use the code?
Do any new features or code changes warrant additional documentation?
Is the documentation clear and well written?
7. Inspect naming conventions
Clear naming conventions make it easier to read and understand code. When programmers choose arbitrary or suboptimal names, even great programs become hard for others to understand.
You can inspect naming conventions by asking:
Have you reviewed the names of variables, constants, class fields, properties, and methods?
Are the names simple and legible?
Do the names fit your business’s naming conventions?
Do the names convey what a function or variable is?
Do the names explain the context or scope of the overall codebase?
Code review checklist template
Want to keep this code review checklist on hand? We made a downloadable PDF to help you along. Hit the download button below for your own code review document template.
What is the purpose of code reviews?
The most apparent advantage of code reviews is ensuring bad code doesn’t make it into production. Still, there are a lot of other benefits, such as knowledge sharing, improving security, and fostering teamwork. Managers conducting code reviews also help organizations achieve greater standardization.
Ensure quality code
By the time you’re done programming, you’re probably tired of staring at the same lines of code. At this point, it’s hard to stay objective and you run the risk of missing mistakes.
That’s when a pair of fresh eyes helps. First, it gives you the peace of mind that someone else will spot any issues in the source code while you make a much-needed coffee (or tea). Reviews also square away debugging early in the development lifecycle instead of patching bugs after release.
Share knowledge and improve teamwork
Even though they can feel like a speed bump during production, code reviews give both the reviewer and the reviewee the opportunity to learn. For example:
The person who reviews code gets to study the source code and style.
The code’s authors can learn from any feedback shared and have the chance to put their lessons into practice.
Both parties benefit from improved communication.
Through this process, code authors and reviewers can brainstorm ideas, discuss objectives, and develop workflows. On top of that, the added collaboration breaks down silos between staff.
Secure code reviews help identify vulnerabilities and security flaws in a manual or automated process. Security lapses can lead to:
Poor overall quality
Less maintainability over time
Higher technical debt
Theft of user information
Preventing security issues in advance saves time and your business’s reputation. An extra few minutes spent checking security will more than pay for itself.
Reduce development costs
Code reviews catch minor issues that could escalate into significant problems. Fixing bugs early can save on dev costs and help the reviewee identify issues to look out for. When it’s profitable and educational, you (literally) can’t afford to skip out on a review.
What not to focus on in a code review
There are better ways to spend your time than checking every detail in a code review. Some areas take priority over others, especially when you're looking to streamline your process. With that in mind, you can avoid focusing on:
Automatable tasks: Incorporate automation into your code review to save time. With automation, you can focus on the tasks AI can't handle. Just make sure to double-check automated work to avoid automation issues.
Aesthetics: While readability matters, you don't need to push the presentation on the code too far. Keep it clear and easy to follow, but don't waste resources on visual flair.
Personal preferences: Standardize code to your business’s or team's preferences, not yours. Sticking to business guidelines keeps everyone's code recognizable to others on the team.
How to improve your code review process
Now that you know what to look for in a code review, you can hone the process. We’ve outlined a few tips to improve your code review process:
Adopt a style guide: Settle style debates by adopting an organization-wide code style guide. It shouldn’t only define superficial elements like whitespace rules or naming conventions, but also how to leverage the features of any programming language.
View code reviews as high-priority tasks: Establish internal guidelines on how quickly code should wrap up (such as a one-day turnaround for code of a certain length or longer if code is significantly larger).
Aim for actionable feedback and probing questions: Rather than commenting on code, ask the author why they formatted the code in a certain way or their intent behind a decision. You’re aiming for a dialogue here.
Replace “you” with “we”: When calling out a problem, format your response in a “We like to do X because Y” statement. Avoid comments like: “You didn’t follow our style guidelines here.” Reminding devs that you’re all working for the same team keeps morale high.
Lean on principles, not opinions: Aim for objective feedback based on coding frameworks or principles. This also provides a learning culture for the author to better understand the “why” behind a certain bit of feedback.
Focus on the aspects that will bring the most value: Don’t focus on every opportunity to improve code during a review. Perfection is great, but given the time and scope of a project, focus on the areas that will make the biggest impact.
Code review FAQ
Still have a few questions about code review guidelines or what to look for in a code review? No sweat, we have answers.
What is the difference between a code review and a code checker?
Code checkers use software to analyze source code. Some organizations use code checkers during development to speed up the review process and reduce the potential for human error. This software uses static analysis to review the source code for bugs, logic errors, style, documentation, and syntax.
What tools streamline code reviews?
Managers don’t have to work through a secure code review checklist on their own. With the right tools, you can speed up the process. We recommend:
Static code analysis tools: Static analysis scans parse source code for errors and security issues. Using one before your review can help you concentrate on harder-to-find problems.
Plug-ins for corrections: Plug-ins for formatting, debugging, and suggesting best practices can help during your review. During the review, these plug-ins point out issues you might’ve missed.
Code review comment trackers: Collaborative review apps and comment tracking tools outline who interacted with code and changed it. When your review goes through more than one phase, these tools can help organize the process.
Which benchmarks and metrics should I keep in mind?
Teams should select software engineering metrics or benchmarks to track the effectiveness of your code reviews and their impact on code quality. Metrics also give teams objective measures to structure code reviews around.
The following four metrics are good starting points to include in your review process:
Reaction time: This metric helps drive collaboration on projects with multiple developers. Simply chart how long it takes a reviewer to respond to a comment addressed to them. Shorter reaction times generally mean a more collaborative, responsive team.
Unreviewed PRs: Leaders refer to unreviewed PRs to see how long code waits for a peer review after it’s submitted. Shorter times point to an effective pipeline where code reviews happen on schedule.
Thoroughly reviewed PRs: This metric gauges the depth of each review. Tracking thoroughly reviewed PRs ensures that no one rubber stamps their reviews.
Iterated PRs: You can see how often code reviews result in fixed bugs or improved quality through iterated PRs. A high number of iterated PRs means your code reviews result in measurable improvements.
How many lines of code should I review at once?
For best results, review no more than 400 lines of code at a time. Any more than that, and you risk missing bugs, logic flaws, and other defects. Better yet, if you can limit yourself to 200 lines of code at a time, you'll have the most success.
Discover how Pluralsight Flow can level up your code reviews
Don't only look at code reviews as a way for senior developers to provide feedback to junior members. Instead, code reviews let the entire team improve, learn, and share knowledge. And by following our code review document template, you can weave this improvement into every session to make each code review count.
Need to improve your collaboration for better code reviews? Pluralsight Flow can track responsiveness and iteration time to prevent unintentional bottlenecks and knowledge silos. By scheduling a demo, we'll show you how Flow can help organize employees around essential tasks and automate the rest.
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