Peer review (assign-reviews and purge-review-teams commands)

Peer reviewing is an important part of a programming curriculum, so of course RepoBee facilitates this! The relevant commands are assign-reviews and purge-review-teams. Like much of the other functionality in RepoBee, the peer review functionality is built around teams and 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.


The commands assign-peer-reviews, purge-peer-review-teams and check-peer-review-progress have been renamed assign-reviews, purge-review-teams and check-reviews, respectively. The functionality is unchanged, and the old commands will continue to work until v2.0.0 is released. At that point, the old commands will be removed.

Getting started with peer reviews using assign-reviews

The bulk of the work is performed by assign-reviews. Let’s have a look at the help message (i.e. run repobee assign-reviews -h):

$ repobee assign-reviews -h
usage: repobee assign-reviews [-h]
                               (-sf STUDENTS_FILE | -s STUDENTS [STUDENTS ...])
                               [-o ORG_NAME] [-g GITHUB_BASE_URL] [-t TOKEN]
                               [-tb] -mn MASTER_REPO_NAMES
                               [MASTER_REPO_NAMES ...] [-n N] [-i ISSUE]

For each student repo, create a review team with pull access named
<student>-<master_repo_name>-review and randomly assign other students to it.
All students are assigned to the same amount of review teams, as specified by
`--num-reviews`. Note that `--num-reviews` must be strictly less than the
amount of students.

optional arguments:
  -h, --help            show this help message and exit
  -sf STUDENTS_FILE, --students-file STUDENTS_FILE
                        Path to a list of student usernames.
  -s STUDENTS [STUDENTS ...], --students STUDENTS [STUDENTS ...]
                        One or more whitespace separated student usernames.
  -o ORG_NAME, --org-name ORG_NAME
                        Name of the target organization
  -g GITHUB_BASE_URL, --github-base-url GITHUB_BASE_URL
                        Base url to a GitHub v3 API. For enterprise, this is
                        usually `https://<HOST>/api/v3`
  -t TOKEN, --token TOKEN
                        OAUTH token for the GitHub instance. Can also be
                        specified in the `REPOBEE_OAUTH` environment
  -tb, --traceback      Show the full traceback of critical exceptions.
                        One or more names of master repositories. Names must
                        either refer to local directories, or to master
                        repositories in the target organization.
  -n N, --num-reviews N
                        Assign each student to review n repos (consequently,
                        each repo is reviewed by n students). n must be
                        strictly smaller than the amount of students.
  -i ISSUE, --issue ISSUE
                        Path to an issue to open in student repos. If
                        specified, this issue will be opened in each student
                        repo, and the body will be prepended with user
                        mentions of all students assigned to review the repo.
                        NOTE: The first line is assumed to be the title.

Most of this, we’ve seen before. 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 --github-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 spam, ham and eggs (see Setup student sepositories).

$ repobee assign-reviews -mn master-repo-1 -sf students.txt --num-reviews 2
# step 1
[INFO] created team spam-master-repo-1-review
[INFO] created team eggs-master-repo-1-review
[INFO] created team ham-master-repo-1-review
# step 2
[INFO] adding members eggs, ham to team spam-master-repo-1-review
[INFO] adding members ham, spam to team eggs-master-repo-1-review
[INFO] adding members spam, eggs to team ham-master-repo-1-review
# steps 3 and 4, interleaved
[INFO] opened issue eggs-master-repo-1/#1-'Peer review'
[INFO] adding team eggs-master-repo-1-review to repo eggs-master-repo-1 with 'pull' permission
[INFO] opened issue ham-master-repo-1/#2-'Peer review'
[INFO] adding team ham-master-repo-1-review to repo ham-master-repo-1 with 'pull' permission
[INFO] opened issue spam-master-repo-1/#2-'Peer review'
[INFO] adding team spam-master-repo-1-review to repo spam-master-repo-1 with 'pull' permission

The following steps were performed:

  1. One review team per repo was created (<student>-master-repo-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 title can then be regexed in the upcoming check-review-progress to see which students assigned to the different peer review teams have created their review issue. Of course, other schemes can be cooked up, but that is my current vision of how I myself will use it. 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 with purge-review-teams).

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 master-repo-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 master-repo-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 master-repo-2 -sf students.txt --num-reviews 2 --issue
[INFO] created team spam-master-repo-2-review
[INFO] created team eggs-master-repo-2-review
[INFO] created team ham-master-repo-2-review
[INFO] adding members ham, eggs to team spam-master-repo-2-review
[INFO] adding members spam, ham to team eggs-master-repo-2-review
[INFO] adding members eggs, spam to team ham-master-repo-2-review
[INFO] opened issue eggs-master-repo-2/#2-'Review of master-repo-2'
[INFO] adding team eggs-master-repo-2-review to repo eggs-master-repo-2 with 'pull' permission
[INFO] opened issue ham-master-repo-2/#2-'Review of master-repo-2'
[INFO] adding team ham-master-repo-2-review to repo ham-master-repo-2 with 'pull' permission
[INFO] opened issue spam-master-repo-2/#2-'Review of master-repo-2'
[INFO] adding team spam-master-repo-2-review to repo spam-master-repo-2 with 'pull' permission

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.

Cleaning with purge-review-teams

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). Therefore, the purge-review-teams command can be used to remove all peer review teams for a given set of student repos. Let’s say that we’re completely done with the peer reviews of master-repo-1, and want to remove the review teams. It’s as simple as:

$ repobee purge-review-teams -mn master-repo-1 -sf students.txt
[INFO] deleted team eggs-master-repo-1-review
[INFO] deleted team ham-master-repo-1-review
[INFO] deleted team spam-master-repo-1-review

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). purge-review-teams 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 master-repo-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 master-repo-2 -sf students.txt -r '^Peer review$' (assuming the naming conventions were followed!). Take appropriate action if you find any reviews already posted (appropriate being anything you see fit to alleviate the situation of affected students possibly being assigned new repos to review).
  2. Purge the review teams with repobee purge-review-teams -mn master-repo-2 -sf students.txt
  3. Close all review issues with repobee close-issues -mn master-repo-2 -sf students.txt -r '^Review of master-repo-2$'
  4. Create a new file apologetically explaining that you messed up:
Review of master-repo-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 master-repo-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 and purge-review-teams 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 master-repo-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.