ESM Config File Support

[npetruzzelli]

#3677

• Description to be updated
• Tests to be updated

[AppVeyorBot]

✅ Build karma 2987 completed (commit 251ec7ab15 by @npetruzzelli)

[karmarunnerbot]

✅ Build karma 590 completed (commit 251ec7ab15 by @npetruzzelli)

[karmarunnerbot]

✅ Build karma 589 completed (commit 251ec7ab15 by @npetruzzelli)

[npetruzzelli]

@devoto13 - Does Karma currently need to support any versions of node that doesn't support import()? (versions 11 and below).

[devoto13]

Yes, Karma still supports Node 10, but it will be dropped in the next major release as Node 10 has reached the end of life in April. I would suggest to let this PR hang for a bit longer, until we start a branch for the next major release, so we need less cleanup to do.

[npetruzzelli]

Sounds like a good plan to me.

[loynoir]

Might I ask about when, will this go into master? 😂

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In case, someone search issue and come here like me, here's my quick workaround using require hook.

#3677 (comment)

[npetruzzelli]

At the very least I would have to merge in the latest master branch to bring this current. I think this repo also had a period of downtime when continuous integration was being updated. ( I wasn't able to follow that too closely).

Realistically, this isn't going to be the PR that gets merged, for a few reasons:

1. Karma 6.x MUST support Node.js version 10
   • to change this is a breaking change, which requires a new major version (Karma 7.x)
   • a Node feature required to support this did not appear until Node 11.x
2. Karma 7.x is expected to rewrite significant chunks of config code (deprecating/dropping support for some things to make the code more maintainable)
   • as a result, how import() is supported may change a bit as well

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@devoto13 - is there a milestone / issue tag / some kind of tracker that lists what needs to be done before a pre-release branch for Karma 7.x is made available for contributions? I might have some time this month/next month to make a contribution

[devoto13]

@npetruzzelli CI is fixed now. I think it's mainly some maintainers' time to implement/review/test/land breaking changes, so we don't end up being stuck in pre-release mode for a long time and probably @jginsburgn's approval to start working on the next major 😄

There is #3503 tracking breaking changes I would like to make (not necessarily all of them) + some of the open PRs.

It is pretty hot time at work now, so I'm not sure when I'll have some time to look into it.

Note that it's possible to install karma from GitHub as well. So if you rebase this PR, people can install it using similar approach as #3726 (comment).

[npetruzzelli]

Got it, if I have a chance, I will at least try to update this branch. Thank you.

In the mean time, @loynoir may be interested in: #3677 (comment)

It requires 1 extra file, but you won't need any additional command line arguments when running node. Use what works best for you.