Unit tests for library

[hmuurine]

Summary

Added some Unit tests for the library project:

• Added Jest dependencies and configuration for running unit tests with npm run test
• Added initial unit tests for the public API:
  • Config: test setting & getting configuration, initial settings, persisting data to URL
  • AFKController: test that AFK timers and events work as expected
  • PixelStreaming: test mocked WebSocket connection, mocked WebRTC connection, mocked video playback, events emitted in various stages of the connection process, statistics emitter, data channel send/receive
• Mocks for WebSocket, MediaStream and WebRTC classes that are not natively supported in Jest/Node/jsdom test environment

Test Plan

• Ran the unit tests and verified that they worked
• Broke some of the functionality deliberately and verified that this was caught in unit tests

[vshjxyz]

Huge one! That's awesome, we should leverage (if possible) having a public repo to integrate coverage reports into PRs to keep track and avoid merging PRs without enough coverage. Since this is a library aimed to be consumed by multiple clients that can also help on external contributions, but I'm probably thinking too far ahead (?)

[lukehb]

Amazing PR! Great work.

A few additional requests on top of the comments I have already left:

1. Can it also include a github action for running these tests against PRs that touch the Frontend/library files?
2. Can you update frontend readme.md informing users how to run these tests by hand.

[lukehb]

Left some minor comments.

[hmuurine]

1. Can it also include a github action for running these tests against PRs that touch the Frontend/library files?

Added an action that runs the unit tests if Frontend/library/** files change. The action is run for master commits and all PRs that have target branch master. You can see the actions triggered already in this PR. Also tested that test failures are properly detected:

2. Can you update frontend readme.md informing users how to run these tests by hand.

Done in a1c9f46

[lukehb]

lgtm!