Adds the configuration for PnP/Typescript

[arcanis]

The fork-ts-checker-webpack-plugin package just released an update that allows to specify custom resolution schemes. This makes it possible for Create-React-App to have native PnP support even when using TypeScript.

I've tested this diff locally and it seemed to work.

[johnnyreilly]

Fast work!

Question: I don't see usage of the https://github.com/arcanis/pnp-webpack-plugin in this PR. Is use of the pnp-webpack-plugin no longer required when working with webpack?

[arcanis]

Until webpack/enhanced-resolve#168 gets merged the pnp-webpack-plugin package is needed for everything that uses enhanced-resolve (basically Webpack itself). Since it's already been configured in #5136 I don't need to add anything else.

In the case of TypeScript, since it uses its own resolution instead of enhanced-resolve, the only package that I need to add is ts-pnp, which connects the living PnP environment with the existing TypeScript resolution algorithms.

[ianschmitz]

Thanks @arcanis. Does Jest work as expected with this PR?

[arcanis]

Yep - running yarn test then pressing a got the default test green.

As far as I can remember, Jest just uses Babel to strip the TS types, so no particular TS resolution involved - it simply uses the classic Jest resolution (which supports PnP out of the box since 24.5).

[crubier]

Can't wait for this aha

[arcanis]

Any blocker?

[iansu]

No, I think this looks good. Thanks for the reminder. 😀

[iansu]

Thanks! ❤️