feat(server): expose server event lifecycle in public API

[nikaspran]

Return the EventEmitter instance so that it's possible to into various lifecycle events. Add a browsers_ready event so that it's possible to know when the karma server has finished starting up.

Enables and partially resolves #1037

I am very interested in resolving #1037 (it's breaking our grunt and gulp builds), so if this is not quite the way you want it to be done, let me know and I'll do it differently! :)

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[nikaspran]

I signed it!

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CLAs look good, thanks!

[dignifiedquire]

So in general I like the approach, though I would prefer not returning the globalEmitter from the start function. In my mind the code (not only yours) needs to be refactored in a way that the interacting api would look like

var karma = require('karma')

karma.on('browsers_ready', function (event) {
  // ...
})

karma.start()

but I'm not a 100% sure yet what the best way is to introduce these changes into the code base.

[nikaspran]

Thank you for taking a look at this :)

It seems quite a major undertaking to refactor everything but I agree it's the best idea longterm. I could take a stab if it's not in the near future for any of the regular maintainers.

One option to have this quickly and then still support easy migration/backwards compatibility later is to return a subset of the emitter, sort of an interface object. So something like this:

{on: globalEmitter.on.bind(globalEmitter), ...}

Then, in the future, it could just start returning karma itself. I think there's a general need to expand the public API a little bit to enable more diverse workflows.

[dignifiedquire]

So it turned out, it wasn't that hard to do :) see #1485 and feel free to give it a test drive

[nikaspran]

Oh, that's actually impressively quick! It seems like it will do the trick quite well. I think we're good to close this PR and the issue I mentioned if #1485 goes through. I'll play around with your branch tomorrow.

👍

[dignifiedquire]

Great