New Screen Recording Feature for Lighthouse Tests

[CaryXiao1]

Hi Oppia developers!

Just wanted to notify everyone about a new feature that the Dev Workflow team has worked on and has pushed to develop: we have enabled screen recording functionality for the Lighthouse Puppeteer Script, both in the GitHub PR testing suite and on local tests with the --record_screen argument.

What is Lighthouse Puppeteer and why are we screen-recording it?
Puppeteer is a JavaScript library that we use to navigate to specific Oppia web pages, which are then used by Lighthouse to measure the performance and accessibility of a given website. However, lighthouse tests might fail because the puppeteer script fails to properly set up the given web page. If you are trying to debug this flaking behavior or determine whether your failing lighthouse tests are due to a puppeteer script flake, the outputted screen recordings might aid in your debugging and help you follow the console log.

How do you perform this screen recording?
For failed tests on GitHub, the video file is automatically uploaded as an artifact titled "ffmpeg-puppeteer-video". If you are running locally, make sure to add the "--record_screen" argument when calling "python -m scripts.run_lighthouse_tests", and the video will be saved in the folder "ffmpeg-video" in the folder containing your oppia branch.

For more information on this new functionality, please see https://github.com/oppia/oppia/wiki/Lighthouse-Tests#failing-lighthouse-puppeteer-script. Happy coding!