Top 10 Code Review Best Practices

Types of Code Reviews

There are two main types of code reviews: 1. Formal code review and 2. Lightweight code review.

Formal Code Review

As the name suggests, formal code reviews are based on a structured process to find defects in code, specifications, and designs. This approach follows established guidelines and involves multiple reviewers. The most popular form of formal code review is Fagan Inspection, which consists of six steps: Planning, overview meeting, preparation, inspection meeting, casual analysis, reworking, and follow-up.

However, formal code reviews can be more time-consuming and resource-intensive than other types.

Lightweight Code Review

Lightweight code reviews are commonly used by development teams and not typically by testers. This approach is often followed when the code review is not life-threatening or when the impact on software quality is less critical.

There are four subtypes of lightweight code review:

Instant Code Review

Also known as pair programming, this type involves two developers working together on the same computer—one writes code while the other reviews it in real time. Such a type is highly interactive and helps in knowledge sharing and spotting bugs.

Synchronous Code Review

In synchronous code review, the author produces the code and asks the reviewer for feedback immediately after coding. The coder and reviewer then discuss and improve the code together, involving direct communication and real-time discussion.

Asynchronous Code Review

Similar to synchronous code review, but the code authors and reviewers do not have to look at the code at the same moment. This approach allows flexibility and is especially beneficial for developers working across various time zones, where remote teams can especially benefit from AI-assisted code reviews.

Team Code Review

This type is used for specific situations where different roles are assigned to reviewers. It enables more in-depth reviews and provides various perspectives. For team code reviews, tools such as code review platforms, version control systems, collaboration platforms, and AI support for remote code reviews are often used.

Choose the correct code review type based on your team's strengths, weaknesses, and the unique factors of your organization.

Now that we've covered the main types of code reviews, let's explore the best practices to make them effective.

Introduction

Code review is all about improving code quality, but it can be a nightmare for engineering managers and developers when not done correctly. This article outlines the top 10 code review best practices, providing actionable guidance for developers and engineering managers who want to enhance code quality and team productivity. Following these code review best practices is crucial for promoting collaboration, improving code readability, and fostering a positive team culture. By adhering to these best practices, teams can overcome common code review challenges and streamline the entire development process.

Code Review Best Practices

Create a Code Review Checklist

A code review checklist provides clear expectations for reviews by listing specific criteria and questions to consider. Code review checklists help reduce conflicts by creating a shared understanding around the same review criteria.

Some necessary quality checks include:

• Readability and maintainability: Is the code easy to read and maintain?
• Uniform formatting: Does the submitted code use consistent indentation, spacing, and naming conventions?
• Testing and quality assurance: Are there thorough testing and quality assurance processes, including test coverage?
• Boundary testing: Are extreme scenarios and boundary conditions explored to identify hidden problems?
• Security and performance: Does the code ensure security and performance by using the best code quality tools for 2024?
• Architectural integrity: Is the code scalable, sustainable, and built on a solid architectural design?
• Coding guidelines: Does the code follow the team’s coding guidelines?

When reviewing code, consider these questions:

• Am I able to understand what the code does?
• Is the code functioning as expected?
• Is the code fulfilling the regular requirements?

This first pass allows you to know what to look for in a code review, set clear expectations, and focus on priorities. Teams should customize the checklist to their own practices and review criteria.

Transitioning from establishing clear review criteria, let's look at how to foster a positive and collaborative code review culture.

Foster a Code Review Culture

The code review process should be an opportunity for growth and knowledge sharing, not a critique of developers' abilities. Effective code reviews support knowledge sharing across the whole team.

To create a culture of collaboration and learning:

• Establish code review guidelines that emphasize constructive feedback, respect, and empathy.
• Encourage pair programming for complex issues during development. Pair programming is when two developers work together at one workstation, with one writing code and the other reviewing in real time.
• Praise good code, not just point out issues.
• Clearly communicate the goals of code review and specify the roles and responsibilities of reviewers and authors.

This approach helps the development team understand the purpose behind code review and view it as a way to improve their coding abilities and skills. Keeping a clear quality bar helps teams stay consistent, and great code reviews reinforce that standard over time.

With a collaborative culture in place, the next step is to ensure feedback is constructive and actionable.

Provide Constructive Feedback

One of the most important code review practices is to provide feedback that is specific, honest, and actionable. Before requesting peer input, authors should do a self-review to catch obvious mistakes. Constructive feedback is essential for building rapport within your software development team.

Feedback should:

• Point out the right direction rather than create confusion.
• Include suggestions, highlight potential issues, or point out blind spots.
• Explain the ‘Why’ behind your feedback to reduce follow-ups and provide necessary context.

Authors should provide clear descriptions of changes and use code comments to annotate each code change with the reasoning behind it. Comments should be written clearly and concisely.

This helps improve the skills of software developers and produces better code, resulting in a high-quality codebase—especially when reviewers avoid common mistakes during code reviews. Clear review comments and suggested changes are also easier to act on when reviewers understand the reasoning.

After establishing effective feedback, it's important to manage the size and scope of code changes for optimal review.

Aim for Small, Incremental Changes

Instead of reviewing all changes at once, focus on small sections to examine all aspects thoroughly. Breaking changes into small, manageable chunks helps identify potential issues and offer suggestions for improvement.

Follow these steps for effective incremental reviews:

1. Break large changes into smaller pull requests (PRs).
2. Use a separate commit for each logical change to make the review clearer.
3. Review each change thoroughly, focusing on one aspect at a time.

Smaller PRs allow developers to understand code changes quickly, and reviewers can provide more focused and detailed reviews. Reviewing code in smaller pull requests helps catch logic errors more reliably, and reviewing more than 400 lines of code reduces defect detection.

This approach leads to a deeper understanding of the code's impact on the overall project, which is especially important when shipping a new feature and optimizing code reviews to boost developer productivity.

With manageable changes, it's also important to measure the effectiveness of your code review process.

Incorporate Code Review Goals and Capture Metrics

According to Goodhart's law, “When a measure becomes a target, it ceases to be a good measure.”

To measure the effectiveness of code review, set tangible goals to provide a quantifiable picture of how your code is improving. Use metrics to determine the efficiency of your review and analyze the impact of process changes. These metrics should support better decisions, not pressure reviewers into faster approvals at the expense of quality.

Consider tracking these key metrics:

• Inspection rate: The speed at which code is reviewed in a timely manner.
• Turnaround time: The time it takes for feedback and review cycles to complete.
• Defect rate: The number of defects found divided by the number of hours spent on a code review.
• Defect discovery rates: How often issues are identified during review.
• Defect density: The defect count divided by thousands of lines of code.

You can use metrics-driven code review tools to decide in advance the goals and how to measure effectiveness. AI in the code review process can help identify patterns in code changes when analyzing review metrics.

Once you have metrics in place, it's important to pace your reviews to maintain quality and avoid burnout.

Don't Rush your Review

To ensure effective code reviews, avoid reviewing too much code at once. Keep these three key points in mind:

• Don't review code for longer than 60 minutes to prevent fatigue.
• Limit your review to 200-400 lines of code at once.
• Plan for 3 seconds of review time per line of code.

Code reviews should also be prompt, ideally within hours, so authors are not left waiting. Google recommends fast reviews to avoid blocking authors, and AI-powered PR summaries with estimated review time can help prioritize reviews without sacrificing quality.

Reviewing code continuously can reduce focus and attention to detail, making reviews less effective and increasing the risk of burnout. Conduct code review sessions often and in short sessions, encourage breaks, and set boundaries. If the core change is sound, minor suggestions should not block progress.

After pacing your reviews, consider how reviewer rotation can further improve your process.

Rotate Code Reviewers Regularly

Relying on the same code reviewers consistently can cause burnout and negatively impact the software development process over time.

Encourage a rotation approach:

• Different team members participate in reviewing code.
• This brings in various skill sets and experience levels, promoting cross-learning and a well-rounded review process.
• It provides different points of view, leading to better solutions and fewer blind spots.

With this approach, team members become familiar with different parts of the codebase, avoid bias in the review process, and understand each other's coding styles.

Next, let's discuss the importance of documenting code review decisions for future reference.

Always Document Code Review Decisions

Documenting code review decisions is essential for understanding the overall effectiveness of the code review process. Ensure that you record and track the code review outcome for future reference. Good commit messages help future reviewers understand why a change was made, making it easier for those who may work on the codebase in the future.

Documentation provides insights into the reasoning behind certain choices, designs, and modifications. It helps keep historical records—changes made over time, reasons for those changes, and any lessons learned during the review process. Documenting decisions should also capture review outcomes after updates are made. This accelerates onboarding for new joiners and supports continuous improvement within the development team.

With documentation in place, it's important to focus on coding standards for consistency.

Focus on Coding Standards, Not Personal Preference

Emphasizing coding standards promotes consistency, readability, maintainability, and overall code quality. Automated tools should handle formatting and linting checks before human review.

Personal preferences vary widely among developers. Teams should focus standards on maintainability and readability rather than personal taste, and use automated tools to enforce code formatting and linting instead of debating them in review. This helps address potential issues early in the development process and ensures the codebase remains consistent over time.

Adhering to coding standards makes it easier to scale development efforts and add new features and components seamlessly. Minor style issues, such as whether names appear in alphabetical order, should usually be treated as low priority unless the standard explicitly requires them.

Finally, let's look at how automation can further streamline your code review process.

Automate as Much as Possible

Code review is a vital process, yet it can be time-consuming. Automate what can be automated.

Use code review tools like Typo or other AI-powered code review tools to improve your development workflow to help improve code quality and increase speed, precision, consistency, and overall quality. Make automated checks the first layer of review automation, including static code analysis plus formatting and linting checks. Automated tests and unit tests should verify correctness, but a human reviewer is still needed to assess business logic and intent.

This allows reviewers to spend more time giving valuable feedback, tracking changes, and enabling easy collaboration. It also ensures that changes don't break existing functionality and that automation supports the code review process rather than replacing it.

With automation in place, let's explore a tool that can help streamline your code review workflow.

Typo - Automated Code Review Tool

Typo's automated code review tool identifies issues in your code and auto-fixes them before you merge to master. This means less time reviewing and more time for important tasks. It keeps your code error-free, making the whole process faster and smoother.

Key features:

• Supports top 8 languages including C++ and C#.
• Understands the context of the code and fixes issues accurately.
• Optimizes code efficiently.
• Provides automated debugging with detailed explanations.
• Standardizes code and reduces the risk of a security breach

Learn More About Typo's Automated Code Review

Conclusion

If you prioritize the code review process, do follow the above-mentioned best practices. These code review best practices maximize the quality of the code, improve the team's productivity, and streamline the development process.

Happy reviewing!