Code Reviews

Last updated on 2026-06-22 | Edit this page

Estimated time: 15 minutes

Overview

Questions

  • How do you add reviews to a PR?
  • How do you address requested changes?

Objectives

  • Become familiar with the code review process on GitHub.

Request a Review

Requesting a review can be done within a PR. Click on a PR, then click on “Reviewers” on the right-hand side. Here you can type in and select reviewers for your PR.

Reviewers menu on a Pull Request - includes the text "Select up to 15 reviewers" and a search bar in which a user can start type a GitHub handle
Callout

No reviewers?

At this point, likely no reviewers will appear. You can only directly request reviews from “Collaborators” on your repository.

Add a Review

To add a review to a PR, navigate to the PR in question and click on “Files changed.”

The Pull Request main page with the "Files Changed" tab (far-right option) circled

Within this page, when you hover over a line of text, a + button will appear to the left.

Small example of what the plus (+) symbol looks like for adding comments to a specific line on a PR

Click on the + button to add a comment to that line.

The pop-up dialog to add a comment on Line 6 - includes a Write and Preview section plus buttons to Cancel, Add single comment, and Start a review

At this point, you can “Cancel”, “Add single comment”, or “Start a review.” If you click “Add single comment”, the comment will be added without rendering a review decision. If you click “Start a review”, this will “start” a review.

Callout

Can you see it yet?

At this point, no one can see your review. It is “Pending” until you finish all of your comments.

Once you have finished adding all of the comments, you will need to press the “Review changes” button.

Files changed page with review button highlighted

You will see three options: “Comment”, “Approve”, or “Request changes.”

Callout

Greyed out options?

Are you following along on your own PR? You might notice that you cannot approve or request changes. This is because you are the author! GitHub doesn’t allow authors to do either of these actions.

Discussion

Review a Teammate’s StarSort Fix

Time to be the maintainer! Partner up with another participant (you’ll need to add each other as collaborators, or work on a shared repo). Navigate to their practice repository, open one of their StarSort PRs, and:

  • Add a couple of line comments using the + button — be kind and specific (suggest, don’t just criticize).
  • Submit the review requesting changes.

Address a Review

Review comments can be viewed in the “Conversation” tab as well as in the “Files changed” tab.

An image displaying the main Pull request page (Conversation), on which the review comments appear lumped together with a preview of each line/comment in its own box
An image displaying the Files changed page, on which the review comments appear on each line on which they were added

Incorporating requested changes can be done via command line or through the GitHub GUI. Once addressed and pushed, you can resolved the different conversations and re-request a review.

Discussion

Fix It

Address the changes your partner requested on your StarSort fix, push the updates, then re-request a review from them.

Callout

GenAI: A reviewer’s assistant

AI review assistants (in GitHub, your IDE, or a chat tool) can do a useful first pass — flag likely bugs, summarize a big diff, or check style — before a human looks. Treat their output as suggestions to verify, not verdicts: they miss intent and can be confidently wrong, and a human still owns the approve/merge decision. For research code, mind data/IP policy before sharing a private diff.

And that’s all, folks! You now know much more about GitHub Pull Requests.

Key Points
  • Code reviews are integrated into GitHub Pull requests.
  • Reviewers can approve, request changes, or simply add comments as part of the review process.
  • Good review comments are kind and specific.
  • GenAI can assist a review, but the human owns the merge decision.