Code Review Excellence
Transform code reviews from gatekeeping to knowledge sharing through constructive feedback, systematic analysis, and collaborative improvement.
When to Use This Skill
- Reviewing pull requests and code changes
- Establishing code review standards for teams
- Mentoring junior developers through reviews
- Conducting architecture reviews
- Creating review checklists and guidelines
- Improving team collaboration
- Reducing code review cycle time
- Maintaining code quality standards
Core Principles
1. The Review Mindset
Goals of Code Review:
- Catch bugs and edge cases
- Ensure code maintainability
- Share knowledge across team
- Enforce coding standards
- Improve design and architecture
- Build team culture
Not the Goals:
- Show off knowledge
- Nitpick formatting (use linters)
- Block progress unnecessarily
- Rewrite to your preference
2. Effective Feedback
Good Feedback is:
- Specific and actionable
- Educational, not judgmental
- Focused on the code, not the person
- Balanced (praise good work too)
- Prioritized (critical vs nice-to-have)
❌ Bad: "This is wrong."
✅ Good: "This could cause a race condition when multiple users
access simultaneously. Consider using a mutex here."
❌ Bad: "Why didn't you use X pattern?"
✅ Good: "Have you considered the Repository pattern? It would
make this easier to test. Here's an example: [link]"
❌ Bad: "Rename this variable."
✅ Good: "[nit] Consider `userCount` instead of `uc` for
clarity. Not blocking if you prefer to keep it."3. Review Scope
What to Review:
- Logic correctness and edge cases
- Security vulnerabilities
- Performance implications
- Test coverage and quality
- Error handling
- Documentation and comments
- API design and naming
- Architectural fit
What Not to Review Manually:
- Code formatting (use Prettier, Black, etc.)
- Import organization
- Linting violations
- Simple typos
Review Process
Phase 1: Context Gathering (2-3 minutes)
Before diving into code, understand:
- Read PR description and linked issue
- Check PR size (>400 lines? Ask to split)
- Review CI/CD status (tests passing?)
- Understand the business requirement
- Note any relevant architectural decisions
Phase 2: High-Level Review (5-10 minutes)
- Architecture & Design - Does the solution fit the problem?
- For significant changes, consult Architecture Review Guide - Check: SOLID principles, coupling/cohesion, anti-patterns
- Performance Assessment - Are there performance concerns?
- For performance-critical code, consult Performance Review Guide - Check: Algorithm complexity, N+1 queries, memory usage
- File Organization - Are new files in the right places?
- Testing Strategy - Are there tests covering edge cases?
Phase 3: Line-by-Line Review (10-20 minutes)
For each file, check:
- Logic & Correctness - Edge cases, off-by-one, null checks, race conditions
- Security - Input validation, injection risks, XSS, sensitive data
- Performance - N+1 queries, unnecessary loops, memory leaks
- Maintainability - Clear names, single responsibility, comments
Phase 4: Summary & Decision (2-3 minutes)
- Summarize key concerns
- Highlight what you liked
- Make clear decision:
- ✅ Approve - 💬 Comment (minor suggestions) - 🔄 Request Changes (must address)
- Offer to pair if complex
Review Techniques
Technique 1: The Checklist Method
Use checklists for consistent reviews. See Security Review Guide for comprehensive security checklist.
Technique 2: The Question Approach
Instead of stating problems, ask questions:
❌ "This will fail if the list is empty."
✅ "What happens if `items` is an empty array?"
❌ "You need error handling here."
✅ "How should this behave if the API call fails?"Technique 3: Suggest, Don't Command
Use collaborative language:
❌ "You must change this to use async/await"
✅ "Suggestion: async/await might make this more readable. What do you think?"
❌ "Extract this into a function"
✅ "This logic appears in 3 places. Would it make sense to extract it?"Technique 4: Differentiate Severity
Use labels to indicate priority:
- 🔴
[blocking]- Must fix before merge - 🟡
[important]- Should fix, discuss if disagree - 🟢
[nit]- Nice to have, not blocking - 💡
[suggestion]- Alternative approach to consider - 📚
[learning]- Educational comment, no action needed - 🎉
[praise]- Good work, keep it up!
Language-Specific Guides
根据审查的代码语言，查阅对应的详细指南：
| Language/Framework | Reference File | Key Topics |
|---|---|---|
| React | React Guide | Hooks, useEffect, React 19 Actions, RSC, Suspense, TanStack Query v5 |
| Vue 3 | Vue Guide | Composition API, 响应性系统, Props/Emits, Watchers, Composables |
| Rust | Rust Guide | 所有权/借用, Unsafe 审查, 异步代码, 错误处理 |
| TypeScript | TypeScript Guide | 类型安全, async/await, 不可变性 |
| Python | Python Guide | 可变默认参数, 异常处理, 类属性 |
| Java | Java Guide | Java 17/21 新特性, Spring Boot 3, 虚拟线程, Stream/Optional |
| Go | Go Guide | 错误处理, goroutine/channel, context, 接口设计 |
| C | C Guide | 指针/缓冲区, 内存安全, UB, 错误处理 |
| C++ | C++ Guide | RAII, 生命周期, Rule of 0/3/5, 异常安全 |
| CSS/Less/Sass | CSS Guide | 变量规范,!important, 性能优化, 响应式, 兼容性 |
| Qt | Qt Guide | 对象模型, 信号/槽, 内存管理, 线程安全, 性能 |
Additional Resources
- Architecture Review Guide - 架构设计审查指南（SOLID、反模式、耦合度）
- Performance Review Guide - 性能审查指南（Web Vitals、N+1、复杂度）
- Common Bugs Checklist - 按语言分类的常见错误清单
- Security Review Guide - 安全审查指南
- Code Review Best Practices - 代码审查最佳实践
- PR Review Template - PR 审查评论模板
- Review Checklist - 快速参考清单