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Effective Code Reviews

July 23, 2023

A well-conducted code review is an opportunity for both the author and the reviewer to learn, share knowledge, and contribute to the overall quality of the software. They are our shared journey towards excellence. The following guidelines may help both authors and reviewers carry out this task more efficiently and constructively.

Code reviews serve as a critical quality control mechanism. They provide an opportunity for developers to learn from each other, share knowledge, and collectively contribute to the overall quality of the software. When done right, code reviews can catch bugs early, improve code maintainability, and foster a culture of collaboration and continuous improvement.

However, conducting effective code reviews is an art that requires skill, tact, and a keen eye for detail. In this comprehensive guide, we'll explore the best practices for both authors and reviewers to make the most out of the code review process.

Part 1: Tips for Authors

  1. Be Your Own First Reviewer Before submitting your code for review, take the time to review it yourself. Look for obvious errors, typos, and potential improvements. This self-review helps catch minor issues and ensures that your code is in the best possible shape before involving others.

  2. Break It Down Large, monolithic changes can be overwhelming for reviewers. Instead, break your work down into smaller, logical chunks. This makes it easier for reviewers to understand your changes and provides more focused feedback.

  3. Automate the Mundane Use tools to automate tasks like linting, formatting, and basic error checking. This saves reviewers' time and ensures that your code adheres to the team's coding standards without manual intervention.

  4. Keep It Focused Your changes should be as specific and narrowly scoped as possible. Avoid including unrelated changes, as they can confuse reviewers and increase the likelihood of introducing errors.

  5. Be Open to Feedback Remember that code reviews are opportunities for growth. Accept constructive criticism graciously and view it as a chance to learn and improve.

  6. Communicate Clearly When responding to review comments, be explicit about the changes you've made. Even if you've implemented a suggestion verbatim, it's helpful to acknowledge it directly.

  7. Don't Neglect Documentation Good documentation is just as important as the code itself. Make sure to include relevant comments, update existing documentation, and provide any necessary context.

Part 2: Tips for Reviewers

  1. Understand the Big Picture Before diving into the details, take a step back and consider how the changes fit into the overall system. Ensure that the code is architecturally sound and aligns with the project's goals.

  2. Prioritize Readability Code is read more often than it is written. As a reviewer, focus on ensuring that the code is clear, concise, and easy to understand. Look for opportunities to improve variable names, simplify complex logic, and add clarifying comments.

  3. Look for Edge Cases Pay attention to potential edge cases and error handling. Consider what might happen under unusual circumstances and ensure that the code is robust enough to handle them gracefully.

  4. Performance Matters While premature optimization is often discouraged, it's still important to keep an eye out for performance bottlenecks. Look for inefficient algorithms, unnecessary computations, or resource leaks that could impact the system's scalability.

  5. Verify Test Coverage Make sure that the changes are accompanied by appropriate tests. Good test coverage helps catch regressions and ensures that the code behaves as expected.

  6. Be Constructive and Specific When providing feedback, focus on the code, not the developer. Be specific in your comments and provide actionable suggestions for improvement. Remember to highlight positive aspects of the code as well.

  7. Know When to Nitpick While it's important to maintain consistency and adhere to coding standards, avoid getting bogged down in minor stylistic issues. Automated tools can handle most formatting concerns, allowing reviewers to focus on more substantive matters.

Part 3: Fostering a Positive Code Review Culture

  1. Establish Clear Guidelines Develop a set of code review guidelines that outline expectations for both authors and reviewers. This helps ensure consistency and sets a baseline for the review process.

  2. Encourage Collaboration Promote a culture of collaboration and learning. Encourage developers to view code reviews as opportunities for growth rather than personal critiques.

  3. Lead by Example As a leader, model the behavior you want to see in your team. Conduct thorough, constructive reviews and be open to feedback on your own code.

  4. Recognize Good Work Publicly acknowledge developers who consistently write high-quality code and provide valuable feedback during reviews. This positive reinforcement helps foster a culture of excellence.

  5. Continuously Improve Regularly assess and refine your code review process. Solicit feedback from your team and be open to adjusting your approach based on their input.

Part 4: The Code Review Checklist

To ensure that your code reviews are comprehensive and effective, consider the following checklist:

  1. Functionality

    • Does the code fulfill the requirements?
    • Are there any obvious logic errors?
    • Are edge cases and error scenarios handled appropriately?
  2. Readability

    • Is the code easy to understand?
    • Are variable and function names clear and descriptive?
    • Are complex sections of code adequately commented?
  3. Maintainability

    • Is the code modular and reusable?
    • Are there any redundant or duplicate code segments?
    • Is the code testable and loosely coupled?
  4. Performance

    • Are there any obvious performance bottlenecks?
    • Is the code efficient in terms of time and space complexity?
    • Are resources (memory, file handles, etc.) properly managed?
  5. Security

    • Are there any potential security vulnerabilities?
    • Are user inputs properly validated and sanitized?
    • Are sensitive data and credentials handled securely?
  6. Testing

    • Are there adequate unit tests covering the changes?
    • Do the tests cover edge cases and error scenarios?
    • Are the tests maintainable and easy to understand?
  7. Documentation

    • Are code comments clear and informative?
    • Is the high-level documentation updated to reflect the changes?
    • Are any necessary API or user-facing documents updated?
  8. Style and Standards

    • Does the code adhere to the team's coding style guide?
    • Are there any inconsistencies or deviations from the project's conventions?
    • Are any major style changes kept separate from the main changelist?


Code reviews are a powerful tool for improving software quality, sharing knowledge, and fostering a culture of collaboration. By following the guidelines outlined in this article, both authors and reviewers can make the most out of the code review process.

Remember, code reviews are not about perfection or personal criticism. They are about continuously learning, growing, and striving for excellence as a team. Approach them with an open mind, a constructive attitude, and a commitment to creating the best possible software.

Happy reviewing!

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This article, "Effective Code Reviews" is licensed under CC BY 4.0 by Addy Osmani. It was adapted from "How to Make Your Code Reviewer Fall in Love with You," by Michael Lynch, used under CC BY 4.0.