Practical code review checklist for small snippets

1. Confirm the purpose

Start by writing one sentence that explains why the code changed. If the change has no clear purpose, the review will be guesswork. A good purpose can be simple, such as fixing a validation bug, renaming a field, removing debug comments, or improving a display message.

Compare the purpose with the actual diff. If a small text update also changes database access, permissions, payment logic, or file handling, slow down and review the unexpected part separately.

2. Review risky areas first

• User input validation
• Authentication and authorization checks
• Database queries and filters
• Payment or subscription logic
• File upload, deletion, or path handling
• Error messages that expose private details
• External URLs, API calls, and secrets

These areas matter because a small difference can cause a security issue, data loss, or a broken user flow. Treat them differently from simple formatting or wording changes.

3. Check behavior, not only text

A diff shows text changes, but users experience behavior. After reading the changed rows, ask what happens when the input is empty, too long, invalid, duplicated, or unexpected. Check success and failure paths. If an error happens, confirm that the user receives a helpful message and that sensitive details are not exposed.

When possible, run the code with at least one normal case and one edge case. For a comment cleanup task, compare the cleaned output with the original and check strings, URLs, and regular expressions.

4. Decide what to document

Not every change needs a long explanation, but important decisions should be documented. Keep comments that explain unusual choices, compatibility requirements, business rules, or limitations. Remove comments that only repeat the obvious or describe code that no longer exists.

If a comment was removed from code, consider whether the same explanation belongs in a guide, release note, or support article instead.