Lesson 2: The Code Review

A Pull Request without a code review is like a pilot skipping the preflight checklist. Code reviews catch bugs, spread knowledge, and maintain code quality across the team.

What to Look For in a Code Review

1. Correctness

Does the code actually do what it claims?
Are there edge cases that aren't handled?
Could it break existing functionality?

2. Security

Are there hardcoded passwords or API keys?
Is user input validated and sanitized?
Are permissions checked properly?

3. Readability

Can you understand the code without the author explaining it?
Are variable names clear and descriptive?
Are complex sections commented?

4. Performance

Are there unnecessary database queries or API calls?
Could loops be optimized?
Are there memory leaks?

Git Commands for Reviewing

# See what changed between branches
git diff main..feature/user-profile

# List only the files that changed
git diff --name-only main..feature/user-profile

# See statistics (lines added/removed per file)
git diff --stat main..feature/user-profile

# Show a specific commit
git show abc123

Review Etiquette

As a Reviewer:

🟢 Be constructive, not critical. "Consider using X because..." not "This is wrong."
🟢 Explain why, not just what. "This could cause a memory leak because..."
🟢 Praise good code. "Nice abstraction here!" boosts morale.
🟢 Use suggestions, not demands. Most platforms have a "Suggest changes" feature.

As an Author:

🟢 Don't take it personally. Reviews improve the code, not judge you.
🟢 Respond to every comment. Even if it's just "Done!" or "Good point, fixed."
🟢 Push fixes as new commits. Makes it easy for the reviewer to see what changed.

Common Review Comments in DevOps

| Comment | Meaning | |---------|---------| | "LGTM" | "Looks Good To Me" — Approved! | | "nit:" | Minor suggestion, not a blocker | | "blocking:" | Must be fixed before merging | | "question:" | Need clarification, not necessarily a problem |

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Mission Objective

Practice reviewing changes:

Full diff: Run git diff main..feature/user-profile to see all changes.
File list: Run git diff --name-only main..feature/user-profile to see which files changed.
Quick stats: Run git diff --stat main..feature/user-profile to see lines added/removed.

Pro Tip

Set up CI/CD checks to run automatically on every Pull Request. This way, tests, linting, and security scans happen before a human even looks at the code. It saves everyone's time.