🧰 The Complete Code Review Checklist – A Practical, Reusable System

31 May 2025 - 5 mins read time
Tags: Ruby CodeReview ReusableSystem QuickNotes

“Good code is read more often than it is written.”

Here’s a systematic, concrete checklist you can reuse to review any repo — big or small, old or new — to judge, document, and improve its coding standards.


The Complete Code Review Checklist

📌 Why a checklist?

A consistent review checklist helps you:

This guide organizes code review into 8 core dimensions, with concrete examples and ideal patterns.

✅ 1. Project Structure & Organization

What to look for Why it matters Ideal examples
Clear folder structure Easier to navigate, scales as code grows app/, lib/, spec/
Descriptive file & class names Find code faster user_serializer.rb
Logical module boundaries Decouples concerns Payment::StripeClient vs PaymentService
README with install & usage Helps newcomers Install, usage, examples, env vars

Tip: Small repos can skip complexity, but structure should still be intentional.

✏ 2. Code Clarity & Readability

What to look for Why Ideal
Consistent formatting Read faster Indentation, line length
Meaningful names Self-documenting fetch_character vs fc
Small functions/classes Easier to test & reuse Methods <~20 LOC
Comments explaining why Show intent # we retry here because API occasionally fails

Anti-pattern: Comments that explain what obvious code does.

📐 3. Design & Architecture

What to look for Why Ideal
Clear separation of concerns Flexibility & maintainability HTTP logic vs parsing logic
Composition > inheritance Avoid deep trees Use modules or delegation
Encapsulation Safer changes Mark helpers private
Extensibility Handle future features Strategy pattern, small interfaces

Red flags:

🧰 4. Idiomatic Language Use

What to look for Why Ideal
Language idioms & stdlib Clearer, robust Ruby: map, select, safe nav &.
Avoid reinventing the wheel Fewer bugs Use Time.parse instead of manual parsing
Consistent naming conventions Predictable API snake_case in Ruby

🧪 5. Tests & Testability

What to look for Why Ideal
Unit tests for core logic Confidence to refactor spec/ folder
Clear test descriptions Understand failures it "returns status 404 when not found"
Isolate external APIs Faster, reliable Mocks/stubs
Coverage for edge cases Fewer surprises Empty input, bad data

Extra: Consider integration tests or contract tests for APIs.

📝 6. Documentation

What to look for Why Ideal
README covers install, usage Quick start bundle install, npm start
Explains env vars & secrets Easier onboarding API_KEY=...
Code comments for tricky logic Future maintainers “why” this approach was chosen
Example requests/responses Helps consumers JSON snippet in README

🔒 7. Security & Dependency Hygiene

What to look for Why Ideal
.gitignore secrets Prevent leaks .env, config/secrets.yml
No hardcoded API keys Safer deploys Use ENV vars
Dependency versions pinned Reproducible builds Gemfile.lock, package-lock.json
Sanitize user input Avoid exploits Whitelisting, escaping

Tip: Use tools like bundler-audit or npm audit.

⚙️ 8. Tooling & Consistency

What to look for Why Ideal
Linter config Enforce standards .rubocop.yml, .eslintrc.js
Code formatter Uniform style Prettier, rufo
CI/CD config Safer merges .github/workflows/
Hook pre-push checks Catch errors early overcommit, husky

📊 Putting it all together: A repeatable system

Use this in practice:

  1. Clone the repo

  2. Walk through each category, write notes:

    • 👍 What’s good
    • 🛠 What can improve

  3. Prioritize fixes:

    • High: security, test gaps
    • Medium: large classes, naming
    • Low: formatting tweaks

  4. Share findings:

    • As markdown (CODE_REVIEW.md)
    • PR review comments
    • Team retrospective

🧪 Example summary (markdown)

# Code Review – Sample Project

## ✅ Project & Structure
✔ Clear `lib/`, `spec/` folders  
✏ Consider adding usage section in README

## 📐 Code & Design
✔ Methods under 15 lines  
✏ Rename `doWork` → `fetch_and_store_data`

## 🧪 Tests
✏ Add tests for empty response

## 🔒 Security
✔ No secrets committed
✏ Pin HTTP client gem to avoid breaking changes

## 🛠 Tooling
✏ Add `.rubocop.yml` for consistent style

📍 Conclusion

Reviewing code is about more than style — It’s about design, clarity, testability, security, and maintainability.

With this checklist:

✏ Reuse it!