Mutex the workers, to behave more like native jest test runs

[stipsan]

Makes the developer experience a bit nicer, and more like the jest-runner itself: https://github.com/facebook/jest/blob/e566a8f4106ac25b008744ffc42204554fd31cf6/packages/jest-runner/src/index.js#L104-L124

Here's an before/after using jest-runner-prettier on the jest repo itself using these settings:

module.exports = {
  displayName: 'Prettier',
  runner: 'jest-runner-prettier',
  moduleFileExtensions: ['md'],
  testMatch: [
    '**/*.md',
  ],
};

Before:

After:

Love this library btw 🎉 Great stuff 😄

[SimenB]

Woo! This is great.

Note that #1 removes the throat dep, so you might want to re-add it if it's merged before this

[stipsan]

Thanks for the heads up, I'll keep an eye out for it 😄

[keplersj]

I love that you used jest-runner-prettier for this. 😍

[skratchdot]

@rogeliog - Any thoughts on this PR? I just recently started using your lib, but was looking for ways to make my custom runner output look a little more like the other runners I've used (less data in my scrollback history). This PR seems like it might do it.

[rogeliog]

This is awesome!

[rogeliog]

I just published 0.3.0 with this

[stipsan]

@rogeliog great, thanks!!

[skratchdot]

Nice work @rogeliog / @stipsan !! Trying this out now. Thanks!