Effective Code Review Practices and Checklist

After previously writing about the four stages of coding, the author reflects on recent experiences with code review after transitioning roles and mentoring many newcomers. In many Silicon Valley‑scale companies, pull requests (PRs) must receive at least one stamp before merging, with additional stamps required for cross‑project changes or critical areas such as payments.

Before stamping, reviewers leave comments on the shared GitHub PR page. Comments may ask questions, point out issues, or spark discussions that can span dozens of replies, helping the team reach consensus.

The author argues that simply rewriting poor code for others hinders learning, while thorough reviews, though time‑consuming, propagate good practices and multiply productivity across the team.

Reviewing also serves as a learning process for the reviewer, enabling them to spot pitfalls and guide others toward better solutions.

Based on these observations, the author proposes the following checklist for effective code reviews:

Code formatting : Follow the company’s coding style guide to avoid trivial style debates, especially for new hires.

Readability : Keep functions short, use descriptive variable names, avoid deep nesting, and ensure comments are accurate and up‑to‑date.

Corner‑case coverage : Senior engineers should help authors consider all edge cases, particularly business‑logic scenarios.

Error handling : Verify input validation, existence checks, and proper exception handling. For example, a simple snippet should validate that params contains user_id and new_name , confirm the user exists, and handle potential database exceptions.

Tests : Every piece of code needs corresponding test cases, and additional tests should be added for anticipated future modifications.

Small architecture : Organize code within files or classes, extract duplicate logic, define constants centrally, and set appropriate visibility (e.g., private).

Large architecture : Ensure proper file organization, consider helper libraries or inheritance, and maintain consistency with the overall codebase style.

Applying this checklist can catch most obvious issues. The author emphasizes that both writing code and reviewing code are essential skills for engineers, and that a respectful, collaborative review culture benefits everyone.

When disagreements arise, it is acceptable to express a personal preference without blocking the merge, e.g., "I personally would prefer A over B, but no strong opinion." Such diplomacy helps maintain a healthy team environment.

Overall, multiple reviewers reduce errors, spread knowledge, and help engineers adopt better programming habits, as illustrated by the author’s own learning of useful Java and Ruby features through code reviews.