Google Summer of Code 2018 with Oppia


Google Summer of Code is global program to promote open-source development. It is being organized by Google every summer since more than a decade. It runs for 12 weeks from mid May to mid August. Students work with an open source organization on a programming project. It’s a great way to spend the summer break!
I was fortunate enough to be a part of GSoC 2018 under the Oppia Foundation.
Oppia is an online learning tool that enables anyone to easily create and share interactive activities (called ‘explorations’). These activities simulate a one-on-one conversation with a tutor, making it possible for students to learn by doing and get feedback.
Before we move ahead, let me briefly introduce myself. I am Apurv Bajaj, an undergraduate engineering student, pursuing a degree in Computer Science and Economics at BITS Pilani, India. I love to learn and play around with new stuff and believe in “Code for a better world”.
Oppia tends to create a huge difference in the field of education by making it accessible to all and therefore, it completely aligns with my passion!


My project at the Oppia Foundation was “Improving the development workflow”, under the category of infrastructure projects. It was mentored by Kevin Lee and the GSoC organization admins during this period were Anmol Shukla and Sean Lip.
The project was sub-divided into three parts, which later formed the three milestones of the project. They were:

  1. Implement automatic lint checks that catch all common errors before a PR is pushed to GitHub. These checks should run automatically for all contributors before submit (and if this isn’t the case, this should be fixed, or a GitHub linter bot created so that reviewers can assume that PRs are linted prior to review).
  2. Create GitHub bots to automate common tasks, and provide documentation on how to write new GitHub bots for other automatable tasks that arise, going forward. Such tasks may include:
    a. checking CLAs (currently maintained in a Google Form) and directing new contributors to the “Getting Started” instructions if the CLA is not signed.
    b. emailing PR authors when their PR has a merge conflict (e.g. when the develop branch is updated) and providing guidance on how to address it.
    c. warning PR authors if PRs look abandoned, and then auto-closing those PRs after a few more days.
  3. Organize and tidy up the e2e tests, and define policies for what to test. Extend the existing e2e framework to support mobile viewports. Provide further documentation on the extension and restructring of the tests for reference.

The Milestones

Milestone 1

In this milestone, a large number of checks were automated. These checks would automatically run before a developer pushes its changes to the pull request branch, that is, all the checks were a part of the pre-submit checks.

Relevant pull requests:

Additional pull requests:

Milestone 2

The Oppiabot, a GitHub app based on the Probot framework was created as a part of this milestone.
It acts as a helper for the Oppia code repository to maintain the development workflow. It is hosted on Heroku.
The bot currently performs the following functions:

  1. Checks whether a contributor creating a pull request has signed the CLA. It adds a label Needs CLA accordingly.
  2. Checks merge conflict in a pull request and notifies the author of the pull request if there is a merge conflict. It also adds a relevant label to the pull request.
  3. Checks whether any pull request has gone stale, adds a relevant label and then automatically closes stale pull requests.

The source code for the Oppiabot can be found at This repository has a detailed README file and a wiki which houses all relevant information from development and deployment to testing.
The Oppiabot uses a customized NPM package for the stale check, which was designed as a part of this milestone. The source code for this can be found at

Relevant pull requests:

Milestone 3

As a part of this milestone, the end-to-end tests were extended for mobile devices. Since the test suite was earlier structered for desktop only, it had to be completely re-structered in order to be compatible with both the desktop and the mobile. The mobile tests run on Browserstack which has been integrated with Oppia’s Travis CI.
The existing documentation on the end-to-end tests was also re-organized so that the structure of the tests is clear to any developer at first glance. The documentation also lays stress on the methodology to be adopted for further extension and integration of the tests. It can be found on the End-to-end tests wiki page of the oppia repository.
Also, additional link checks were added as part of this milestone. These were included in the pre-submit checks as well.

Relevant pull requests:

Additional pull requests:


Google Summer of Code 2018 has been a great learning experience for me. In a span of 3 months, I picked up a number of new technologies and got familiar with the fascinating world of open source.
I would like to thank my organization, the Oppia Foundation for such a wonderful GSoC time. I would also like to thank my mentor, Kevin who was always very responsive and ready to help me out whenever I was stuck; the GSoC organization admins, Anmol and Sean for being always there to un-stuck any of the GSoC students; all other mentors and fellow GSoC students and developers for their co-operation and help.
Finally, I would like to thank Google for creating such a wonderful opportunity for the students and the open-source community alike.
That said, this project is quite important from the perspective of the developers, the maintainers and the reviewers at Oppia and brings a lot of ease in their duties.
As an inspiration from this GSoC project, another wonderful project has also been created for Oppia, the “Developer experience” project at I will be leading this project in the course of time!