Peer review (assign-reviews, check-reviews and end-reviews commands)

Peer reviewing is an important part of a programming curriculum, so of course RepoBee facilitates this! The relevant commands are assign-reviews and end-reviews. Like much of the other functionality in RepoBee, the peer review functionality is built around indirect access through teams with limited access privileges. In short, every student repo up for review gets an associated peer review team generated, which has pull access to the repo. Each student then gets added to 0 < N < num_students peer review teams, and are to open a peer review issue in the associated repos. This is at least the the default. See Selecting peer review allocation algorithm for other available review allocation schemes.


Peer review functionality has yet to be implemented for:

  1. The gitlab plugin.
  2. Student groups.

Both of these are planned features, but have no current ETA.

Getting started with peer reviews using assign-reviews

The bulk of the work is performed by assign-reviews. Most of its arguments it has in common with the other commands of RepoBee. The only non-standard arguments are --issue and --num-reviews, the former of which we’ve actually already seen in the open-issues command (see Opening Issues). I will assume that both --base-url and --org-name are already configured in the configuration file (if you don’t know what this mean, have a look at Configuration file). Thus, the only things we must specify are --students/--students-file and --num-reviews (--issue is optional, more on that later). Let’s make a minimal call with the assign-reviews command, and then inspect the log output to figure out what happened. Recall that students.txt lists our three favorite students slarse, glassey and glennol (see Set up student sepositories).

$ repobee assign-reviews --mn task-1 --sf students.txt --num-reviews 2
# step 1
[INFO] Created team slarse-task-1-review
[INFO] Created team glennol-task-1-review
[INFO] Created team glassey-task-1-review
# step 2
[INFO] Adding members glennol, glassey to team slarse-task-1-review
[INFO] Adding members glassey, slarse to team glennol-task-1-review
[INFO] Adding members slarse, glennol to team glassey-task-1-review
# steps 3 and 4, interleaved
[INFO] Opened issue glennol-task-1/#1-'Peer review'
[INFO] Adding team glennol-task-1-review to repo glennol-task-1 with 'pull' permission
[INFO] Opened issue glassey-task-1/#2-'Peer review'
[INFO] Adding team glassey-task-1-review to repo glassey-task-1 with 'pull' permission
[INFO] Opened issue slarse-task-1/#2-'Peer review'
[INFO] Adding team slarse-task-1-review to repo slarse-task-1 with 'pull' permission

The following steps were performed:

  1. One review team per repo was created (<student>-task-1-review).
  2. Two students were added to each review team. Note that these allocations are _random_. For obvious resons, there can be at most num_students-1 peer reviews per repo. So, in this case, we are at the maximum.
  3. An issue was opened in each repo with the title Peer review, and a body saying something like You should peer review this repo.. The review team students were assigned to the issue as well (although this is not apparent from the logging).
  4. The review teams were added to their corresponding repoos with pull permission. This permission allows members of the team to view the repo and open issues, but they can’t push to (and therefore can’t modify) the repo.

That’s it for the basic functionality. The intent is that students should open an issue in every repo they are to peer review, with a specific title. The issues can then be searched by title, and the check-reviews command can find which students have opened issues in the repositories they’ve been assigned to review. Now, let’s talk a bit about that --issue argument.


Assigning peer reviews gives the reviewers read-access to the repos they are to review. This means that if you use issues to communicate grades/feedback to your students, the reviewers will also see this feedback! It is therefore important to remove the peer review teams (see Cleaning up with end-reviews).

Specifying a custom issue

The default issue is really meant to be replaced with something more specific to the course and assignment. For example, say that there were five tasks in the task-2 repo, and the students should review tasks 2 and 3 based on some criteria. It would then be beneficial to specify this in the peer review issue, so we’ll write up our own little issue to replace the default one. Remember that the first line is taken to be the title, in exactly the same way as issue files are treated in Opening Issues.

Review of task-2

Hello! The students assigned to this issue have been tasked to review this
repo. Each of you should open _one_ issue with the title `Peer review` and
the following content:

## Task 2
### Code style
Comments on code style, such as readability and general formatting.

### Time complexity
Is the algorithm O(n)? If not, try to figure out what time complexity it is
and point out what could have been done better.

## Task 3
### Code style
Comments on code style, such as readabilty and general formatting.

Assuming the file was saved as, we can now run the command specifying the issue like this:

$ repobee assign-reviews --mn task-2 --sf students.txt --num-reviews 2 --issue
[INFO] Created team slarse-task-2-review
[INFO] Created team glennol-task-2-review
[INFO] Created team glassey-task-2-review
[INFO] Adding members glennol, glassey to team slarse-task-2-review
[INFO] Adding members glassey, slarse to team glennol-task-2-review
[INFO] Adding members slarse, glennol to team glassey-task-2-review
[INFO] Adding team glassey-task-2-review to repo glassey-task-2 with 'pull' permission
[INFO] Opened issue glassey-task-2/#8-'Review of task-2'
[INFO] Adding team glennol-task-2-review to repo glennol-task-2 with 'pull' permission
[INFO] Opened issue glennol-task-2/#8-'Review of task-2'
[INFO] Adding team slarse-task-2-review to repo slarse-task-2 with 'pull' permission
[INFO] Opened issue slarse-task-2/#9-'Review of task-2'

As you can tell from the last few lines, the title is the one specified in the issue, and not the default title as it was before. And that’s pretty much it for setting up the peer review repos.

Checking review progress with check-reviews

The check-reviews command provides a quick and easy way of checking which students have performed their reviews. You provide it with the same information that you do for assign-reviews, but additionally also provide a regex to match against issue titles. The command then finds all of the associated review teams, and checks which students have opened issues with matching titles in their alloted repositories. Of course, this says nothing about the content of those issues: it purely checks that the issues have been opened at all. --num-reviews is also required here, as it is used as an expected value for how many reviews each student should be assigned to review. It is a simple but fairly effective way of detecting if students have simply left their review teams. Here’s an example call:

$ repobee check-reviews --mn task-2 --sf students.txt --num-reviews 2 --title-regex '\APeer review\Z'
[INFO] Processing glassey-task-2-review
[INFO] Processing glennol-task-2-review
[INFO] Processing slarse-task-2-review
reviewer        num done        num remaining   repos remaining
glennol         0               2               glassey-task-2,slarse-task-2
slarse          2               0
glassey         0               2               glennol-task-2,slarse-task-2

The output is color-coded in the terminal, making it easier to parse. I find this higly useful when doing peer reviews in a classroom settings, as I can check which students are done without having to ask them out loud every five minutes. The next command lets you clean up review teams and thereby revoke reviewers’ read access once reviews are over and done with.

Cleaning up with end-reviews

The one downside of using teams for access privileges is that we bloat the organization with a ton of teams. Once the deadline has passed and all peer reviews are done, there is little reason to keep them (in my mind). It can also often be a good idea to revoke the reviewers’ access to reviewed repos if you yourself plan to provide feedback on the issue tracker, so as not to let the reviewers see it. Therefore, the end-reviews command can be used to remove all peer review teams for a given set of student repos, both cleaning up the organization and revoking reviewers’ read access. Let’s say that we’re completely done with the peer reviews of task-1, and want to remove the review teams. It’s as simple as:

$ repobee end-reviews --mn task-1 --sf students.txt
[INFO] Deleted team glennol-task-1-review
[INFO] Deleted team glassey-task-1-review
[INFO] Deleted team slarse-task-1-review


end-reviews deletes review allocations created by assign-reviews. This is an irreversible action. You cannot run check-reviews after running end-reviews for any given set of student repos, and there is no functionality for retrieving deleted review allocations. Only use end-reviews when reviews are truly done, and you have collected what results you need. If being able to backup and restore review allocations is something you need, please open an issue with a feature request on the issue tracker.

And that’s it, the review teams are gone. If you also want to close the related issues, you can simply use the close-issues command for that (see Closing Issues). end-reviews plays one more important role: if you mess something up when assigning the peer reviews. The next section details how you can deal with such a scenario.

Messing up and getting back on track

Let’s say you messed something up with allocating the peer reviews. For example, if you left out a student, there is no easy way to rectify the allocations such that that student is included. Let’s say we did just that, and forgot to include the student cabbage in the reviews for task-2 back at Getting started with peer reviews using assign-reviews. We then do the following:

  1. Check if any reviews have already been posted. This can easily be performed with repobee list-issues --mn task-2 --sf students.txt -r '^Peer review$' (assuming the naming conventions were followed!). Take appropriate action if you find any reviews already posted (appropriate being anything you see fit to alleviate the situation of affected students possibly being assigned new repos to review).
  2. Purge the review teams with repobee end-reviews --mn task-2 --sf students.txt
  3. Close all review issues with repobee close-issues --mn task-2 --sf students.txt -r '^Review of task-2$'
  4. Create a new file apologetically explaining that you messed up:
Review of task-2 (for real this time!)

Sorry, I messed up with the allocations previously. Disregard the previous
allocations (repo access has been revoked anyway).
  1. Assign peer reviews again, with the new issue, with repobee assign-reviews --mn task-2 --sf students.txt --num-reviews 2 --issue

And that’s it! Disaster averted.

Selecting peer review allocation algorithm

The default allocation algorithm is as described in Peer review (assign-reviews, check-reviews and end-reviews commands), and is suitable for when reviewers do not need to interact with the students whom they review. This is however not always the case, sometimes it is beneficial for reviewers to to interact with reviewees (is that a word?), especially if the peer review is done in the classroom. Because of this, RepoBee also provides a _pairwise_ allocation scheme, which allocates reviews such that if student A reviews student B, then student B reviews student A (except for an A->B->C->A kind of deal in one group if there are an odd amount of students). This implemented as a plugin, so to run with this scheme, you add -p pairwise in front of the command.

$ repobee -p pairwise assign-reviews --mn task-1 --sf students.txt

Note that the pairwise algorithm ignores the --num-reviews argument, and will issue a warning if this is set (to anything but 1, but you should just not specify it). For more details on plugins in RepoBee, Plugins for RepoBee.