Add a test runner for JavaScript

[anhari]

Seems like jest is probably the best choice as the default runner.

See jest-cli documentation.

[alk-mandrianarijaona]

hey @anhari, how can we help to have this feature?

[anhari]

Hey Mika 👋! Sorry for such a delayed response. To be honest, I've been sitting on this one because I'm not sure of the best way to go about it 😅

• Jest doesn't seem to support running a specific test using a line number
• The directory structure for JavaScript projects I've contributed to have varied quite a bit.
• I would want to get it working with TypeScript as well.

It's definitely doable (outside of running a test using the current line number), but I've been a bit mentally stuck on fleshing it out. I think the easiest place to start would be adding the ability to run all of the tests in an opened test file.