2learn

Code Review

What it is

Code review is another person reading a change before it merges, looking for defects the author cannot see. It is a conversation about a diff, with three jobs in order of importance: catch problems that would reach production, confirm the change does what it claims, and spread knowledge of the code between the people who will maintain it. It is not a gate for style preferences and it is not an examination.

Why it matters

Review is the cheapest defect detection there is. A bug found in a diff costs minutes; the same bug found in production costs an incident, a fix and a customer conversation. Review also catches the defects automated checks cannot: a change that is correct but solves the wrong problem, an error path that swallows a failure, a boundary condition the tests do not cover. And because most teams merge several times a day, review is where shared understanding of a codebase is actually built.

In this track

  1. Reading a diff for correctness (01-cs-fundamentals/17-code-review/01-reading-a-diff-for-correctness) — understanding intent, hunting the risky classes of change, and checking the tests as part of the change.
  2. Reviewing for clarity and tone (01-cs-fundamentals/17-code-review/02-reviewing-for-clarity-and-tone) — separating blockers from suggestions and writing comments that improve the code rather than the mood.

Prerequisites

Go deeper

Analytics cookies are set only if you allow them. Nothing is loaded, and nothing is sent, until you choose.