[wip] support aliases

[ChristopherBiscardi]

This adds support for webDependencies alias support. For example, we can alias react to preact/compat.

{
 "snowpack": {
    "webDependencies": [
      "preact",
      "@emotion/preact-core",
      [
        "react",
        "preact/compat"
      ]
    ]
  }
}

---

I still need to get some local tests passing and go back over the code to make sure it's doing what I think it is.

TODO:

• fix: source-pika tests (node 13 only?)
• fix: export tests (node 13 only?) [fixed by rebasing]
• write: alias tests

[FredKSchott]

This looks great, thanks Chris! Will do a deeper review of the code asap.

Looks like master branch got bit by a change to Node.js v13 in todays release. I just pushed a fix to master, so now master should be green.

[ChristopherBiscardi]

current problems: It seems like rollup needs some way to track import React from 'react' back to preact/compat entrypoint. I could write a babel plugin that swaps imports so you'd end up with import React from 'preact/compat' but I don't know enough about rollup to know if that would fix it.

For reference, after installing react-helmet with the webDependencies: [['react', 'preact/compat']] config, I'm working on fixing this error:

➜ yarn snowpack
yarn run v1.19.0
$ snowpack --dest public/web_modules
⠼ snowpack installing... @emotion/preact-core, preact, preact/compat, react-helmet
✖ 'react' is imported by '../../node_modules/react-helmet/lib/Helmet.js', but could not be resolved.
  Make sure that the package is installed and that the file exists.
✖ 'react' is imported by '../../node_modules/react-helmet/lib/HelmetUtils.js', but could not be resolved.
  Make sure that the package is installed and that the file exists.
✖ 'react' is imported by '../../node_modules/react-side-effect/lib/index.js', but could not be resolved.
  Make sure that the package is installed and that the file exists.
✖ 'react' is imported by 'react?commonjs-external', but could not be resolved.
  Make sure that the package is installed and that the file exists.
✔ snowpack installed: @emotion/preact-core, preact, preact/compat, react-helmet. [1.05s]
⚠ Finished with warnings.
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

[FredKSchott]

Take a look at https://github.com/rollup/plugins/tree/master/packages/alias. At best, you can leverage this Rollup plugin directly, but at worse there might still be something useful in the codebase to borrow from.

[ChristopherBiscardi]

alias plugin seems to be working locally. Just have to do some tests+fixes now.

[FredKSchott]

This lgtm, once you figure out broken tests.

The interface may need to change a bit after this, if you don't mind carrying that conversation forward into #236. But overall very +1 on supporting this in some way into the future.

[FredKSchott]

lol assuming we can get rid of this?

[ChristopherBiscardi]

lol whooooops, thanks for the catch

[FredKSchott]

For the broken tests, have you tried rebasing onto master yet?
Update: uh oh, don't spend too much time on this, looks like there was a regression in Node 13.10 affecting got sindresorhus/got#1107

[ChristopherBiscardi]

Rebasing fixed the original export test failure. I think the source --pika stuff is on me

[ChristopherBiscardi]

left a comment on #236 about maybe moving to an object and a separate aliases key now that I know more about how this part of snowpack works. I think this allows us to mess with less of the codebase and keep aliases separate from webDependencies, as well as remote sourcing and such. Aliasing would become "just aliasing" instead of playing a sort of double duty with installing/locking down dependencies.

[FredKSchott]

Feel free to close, if #249 is the new way forward

[FredKSchott]

err, closing because I think I know the answer. but feel free to comment to reopen