Code Review Best Practices

Best Practice: Code Review Best Practices

Code review is the practice of having one or more engineers examine a change before it merges. Google's widely cited engineering practices frame the core principle simply: a reviewer should approve a change once it definitely improves the overall code health of the system, even if it is not perfect. Code review matters because it catches defects, spreads knowledge across the team, keeps the codebase consistent, and creates a record of why decisions were made. Done well, it is fast and respectful; done poorly, it becomes a bottleneck or a source of friction that drives engineers to route around it.

Step-by-Step Implementation Guidance

1. Keep changes small and focused so they can be reviewed quickly and thoroughly.
2. Write a clear description explaining what changed and why.
3. As a reviewer, respond promptly; fast turnaround is a primary metric.
4. Review for correctness, design, tests, naming, and readability, in roughly that priority.
5. Distinguish blocking issues from optional suggestions (label nits clearly).
6. Comment on the code, not the person, and explain the reasoning behind requests.
7. Approve when the change improves code health, not when it reaches perfection.

Common Mistakes Teams Make When Ignoring This Practice

• Submitting huge changes that reviewers skim instead of read.
• Letting reviews sit for days, blocking the author and delaying delivery.
• Demanding perfection and gold-plating instead of net improvement.
• Rubber-stamping approvals without genuine review.
• Giving terse or harsh feedback without rationale.

Tools and Techniques That Support This Practice

• Pull/merge request platforms: GitHub, GitLab, Bitbucket.
• Automated checks (CI, linters, formatters) to handle mechanical issues before human review.
• Code owners files to route reviews to the right people.
• Review checklists and PR templates.
• Metrics on review latency and change size.

How This Practice Applies to Different Migration Types

• Cloud Migration: Review infrastructure-as-code changes for security and cost as carefully as application code.
• Database Migration: Scrutinize schema and data-migration scripts for reversibility and data safety.
• SaaS Migration: Review integration adapters for correct handling of the new provider's contract.
• Codebase Migration: Keep migration changes small and well-described so reviewers can verify behavior parity.

Checklist

• Changes are small and single-purpose.
• Each change has a clear description of what and why.
• Reviews are turned around promptly.
• Feedback distinguishes blockers from optional nits.
• Comments are respectful and include rationale.
• Automated checks run before human review.
• Approval is based on improved code health, not perfection.