import `testing-library/dom` from npm instead of unpkg

[smeijer]

This comment needs to be fixed:

quoting for issue indexing:

This is not the way I want it to be, but I can't get '@testing-library/dom'
to build with Parcel. Something with "Incompatible receiver, Map required".
It works when running parcel in dev mode, but not in build mode. Seems to
have something to do with a core-js Map polyfill being used?
It's now loaded from unpkg.com via ./index.html

https://github.com/smeijer/testing-playground/blob/958a46b4be8520045908ac1d20de8236e45409f5/src/parser.js#L5-L16

[smeijer]

Actually, I think I've changed my mind.

Fetching it from unpkg gives us an advantage. It will allow us to add an option to switch the version of testing-library that's being used.

@marcosvega91 & @MichaelDeBoey, what do you guys think?

[marcosvega91]

I like the idea, can be interesting

[MichaelDeBoey]

Being able to switch the version could be helpful to test possible bugs with, but I'm not sure if we should make this available tbh.
I think we should help strive towards pushing the newest version.

[Siemko]

I hope this helps a bit, in my opinion testing-playground should always aim for the newest version of testing-library. I think it aims to be the guiding light, and we want it to point to the best possible direction. @MichaelDeBoey here is right.

[smeijer]

Some help in fixing the issue would be most welcome 😇

[Siemko]

I'll have a look after my working hours 👀

[smeijer]

I'll have a look after my working hours 👀

Thanks. That would be awesome!

[Siemko]

This one's nasty. Generally speaking, parcel uses core-js@3 from @babel/runtime-corejs3 to provide all the polyfills. Of course map polyfill is not a Map, and there is some checking done. I was trying to play with babel configuration, I can change some settings, but it seems like @babel/runtime-corejs3 is always applied by parcel.

What I know by now:

1. Parcel's not taking .babelrc into consideration during build unless "env" option is specified
2. Providing

"presets": [
    ["@babel/preset-env", { "corejs": false }],
    "@babel/preset-react"
  ],
"plugins": [["@babel/plugin-transform-runtime", { "corejs": false }]],

to both .babelrc root and env.production has no influence on how parcel transforms it.

I'm confused, will keep on working this out tomorrow.

[smeijer]

Yeah, what I remember from another project of mine, is that parcel does do something "smart" with browserslists.

I think we need to write a browserslist file to the testing-library folder before build (or post install)

Also see here: parcel-bundler/parcel#1655 (comment)

If that doesn't work, we have a few options left.

• open an issue at parcel-bunder
• fix the issue in testing lib
• add testing lib as git sub module

The last one is really least preferable in my opinion.