Interacting with Review Board

The web interface of MozReview is powered by Review Board. This article will talk a little about how Review Board works and how we’ve customized it for MozReview.

How Review Board Works

Before we go on to describe how to use Review Board, it is important to have a brief understanding of how Review Board works.

For the patient, a read of the Review Board User Guide is recommended.

For the impatient, some terminology. Note that some of these terms are specific to MozReview.

review request
A request to review a single patch/diff/commit
Responses to a review request
A component of a review that is explicitly tracked as part of the review request
review request series
A collection of review requests all belonging to the same logical group
parent review request
For review request series, the review request that tracks the overall state of the series. This is also known as the root review request.
Refers to a state review requests or reviews can be in where content is not publicly visible and is only available to the person who created it. All review requests and reviews start in the draft state by default.
The act of taking a draft review request or draft review and marking it as public, making it visible to everybody
ship it
This is the term used for granting review or r+ in Bugzilla terminology.
review id
A unique identifier identifying a review request series. This is commonly derived from a bug number and username.

Publishing Commits

When you push commits to the review repository, review requests are created in Review Board. As a refresher:

$ hg push review
pushing to ssh://
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 2 changesets with 2 changes to 2 files (+1 heads)
remote: recorded push in pushlog
submitting 2 changesets for review

changeset:  227233:8943dd91f4c0
summary:    Bug 448604 - Rewrite Firefox on top of Servo
review: (pending)

changeset:  227234:5de956a4f2b5
summary:    Bug 448604 - Remove all XUL usage
review: (pending)

review id:  bz://448604/MattN
review url: (pending)
(visit review url to publish these review requests so others can see them)

The pending in the output says that the review requests are in an unpublished draft state. In other words, only you can see the content that has been uploaded to Review Board.

The first thing you should do is follow the final URL in the output - the review url. You should see a page like the following:


This is the parent (aka. root) review request. It is a special review request that manages the state of all the children review requests.

The metadata on the parent review request is derived from the content of commits you’ve pushed for review. You can see a list of commits and their summary lines that are part of the review.

To publish the collection of review requests, you’ll want to assign reviewers.

Each commit has Reviewers line that shows the reviewer(s) for the commit.

To edit reviewers, click the pencil icon to display an input box. Typing into the input box will display results from Bugzilla’s and Review Board’s shared user database. Here is what that looks like:



The easiest way to find a reviewer is by IRC nickname. You should not need to type the leading colon that exists in Bugzilla.

Once you’ve selected the reviewers for a commit, click OK to stop editing the field.

After you’ve selected a reviewer for each commit, your parent review request will look something like the following:


At this time, you’ll want to click the Publish button on the green notification bar. This will start the process of publishing the reviews in Review Board and updating Bugzilla to reflect that a review is requested.

Reviewing Code

So you’ve been asked to review something on Review Board. You’ve come to the right place to learn.

Mozilla hasn’t customized the review interface of Review Board significantly. So, the Review Board User Guide, particularly the section on Reviewing, is almost completely applicable to MozReview!

We highly recommend reading the Reviewing section of the Review Board User Guide before conducting review. When reading, you may want to pay attention to the following, which may be new concepts if you are coming from Bugzilla code reviews:

Advanced Diff Viewer and Commenting

The diff viewing and commenting mechanism in Review Board is much more advanced compared to Bugzilla/Splinter.

If the lines of context in a review are not sufficient, you can expand context right from the review interface (it just fetches the data from the underlying repository you pushed the commits too).

Intra-line diffs are supported. This means if you only change a single character or line, that is clearly indicated.

Whitespace differences can be shown or hidden dynamically from the interface.

Review comments can be set over multiple lines, allowing reviewers to be clearer about where the comment applies.

Interdiff (showing the diff between multiple versions of the diff) works.

Issue Tracking

When writing comments on reviews, Review Board allows you to open an Issue.

Issues are important comments that are explicitly tracked by Review Board.

When you view a review request, a table of issues is presented. This allows reviewer and code author to track the progress of a review over multiple iterations.

Review Board supports Markdown in many of its multi-line text fields. This includes review comments. Use the power responsibly.
Drafts and Published Reviews
Review comments are in an unpublished draft state by default. You must explicitly click a Publish Review button for your review to be visible by others.
Conversion to Bugzilla Comments

When reviews are published, their content is converted to text and posted to Bugzilla as a comment.

(There is talk of changing this behavior because capturing the rich review interface in Bugzilla comments can be challenging and appears to offer little value over just going to Review Board and looking at the original comments there.)

Granting, Denying, Clearing, and Delegating Reviews

There is a dropdown containing standard Bugzilla review flags (r?, r+, and r-) in the Finish Review dialog in each commit review request. The selected value will be set on the corresponding attachment in Bugzilla when the review is published. There is also a blank value, which will clear the review flag. Since each commit has an associated attachment with review flags in Bugzilla, they need to be reviewed separately.

Note that, if a reviewer has previously left a r+ or r- review, or has cleared the review, resetting it to r? will cause the review flag in Bugzilla to be both set and directed to the reviewer, since a user cannot set a review flag as someone else. If the original r? has never been changed, then it will be left as is, i.e., set by the commit author.

The list of reviewers can be modified by anyone with permission to change the attachment in Bugzilla; click on the edit/pencil icon next to the reviewer list and update the reviewers using their IRC nicks. Changes to the reviewer list need to be published using the Publish button on the green notification bar.

While the parent review request (available from the Review Summary link on any commit review request) provides a collapsed view of all commits and can be useful to get a global view of the whole commit series, reviewers should generally not leave reviews on it. Correspondingly, the review-flag dropdown is disabled on parent review requests.

There is currently no equivalent to feedback+. This workflow is still being discussed.

Working With “Patches”

The review description field contains an url to pull down the commits under review. If you want to view the patch as plain text, import it into a mercurial queue, push it to another tree, etc. this is the way to go.

To pull the commits down use the url provided in the review description, for instance, if the revision is foo:

$ hg pull -r foo

Once it is pulled down you can bookmark it and update to it, which is the recommended way of working with patches:

$ hg bookmark -r foo foo-review
$ hg update foo-review

Or if you still use mercurial queues, you can import it into a mercurial queue:

$ hg qimport -r foo
$ hg qapplied

To get plain text, just use hg export:

$ hg export -r foo-review > foo.patch


$ hg export qtip > foo.patch

Once you’ve finished with a patch, if you’re using bookmarks you can just update to another bookmark and remove the review bookmark:

$ hg update central
$ hg bookmark --delete foo-review

If you’re using queues, you can pop it from your queue and then delete it:

$ hg qpop
$ hg qdelete foo.patch