Add lint rule to disallow require.ensure and System.import

[tharakawj]

Fixes#1524

Also, disallow System.import as it has been deprecated in webpack 2.

[tharakawj]

CI build has failed because the kitchensink template for e2e testing uses require.ensure. I think first we need to add support for dynamic import() and replace require.ensure with import().

[Timer]

You can rebase onto #1538 if you'd like, CI should pass after.

[tharakawj]

I'm not sure how to do it. I'll rebase this with master after #1538 is merged.

[Timer]

No problem. Thanks for the PR!

[Timer]

Hi @tharakawj! #1538 has been merged, could you please rebase this? 😄

[tharakawj]

@Timer Done!
but the build has failed. Any idea??

[gaearon]

The CI log says:

error Received malformed response from registry for undefined. The registry may be down.

I'll just restart the build.

[tharakawj]

It passed! Thanks @gaearon

[gaearon]

This should link to an explanation.

[gaearon]

People seeing this warning might not even be aware import() exists. We should link to some section that clearly explains how to use it.

[Timer]

I don't believe we have docs for this yet. 🙈

@tharakawj, would you like to contribute some? 😄

[gaearon]

One pitfall is we won't want to merge that doc until 0.10 or we'll get tens of issues claiming the feature doesn't work. 😄

[Timer]

We could add the link to the PR's changes/document for now and once it's merged switch it. 🤷‍♀️

[gaearon]

I'm happy to get this PR in as is if you create an umbrella issue for 0.10 mentioning adding the link (and doc) as todo items.

[tharakawj]

@Timer yeah. I would love to. 😄 I can work on the doc. If you like we can add the link to webpack import() documentation for the time being

[gaearon]

A link to https://webpack.js.org/guides/code-splitting-import/#dynamic-import sounds good.

[tharakawj]

Ok. I'll update the PR

[tharakawj]

Done!

[Timer]

@gaearon should we still allow webpack to parse require.ensure since this is only set to warning? master has require.ensure disabled -- I don't want webpack to blow up (says cannot statically analyse deps). Alternatively, we could make this lint rule error out.

[gaearon]

I'm fine with this being a hard error.

[gaearon]

Unrelated, but how does #1538 work inside Jest?

[tharakawj]

@Timer Good point! I'll update the PR

[Timer]

Unrelated, but how does #1538 work inside Jest?

It doesn't, oops! But #1615 fixes that.

---

Thanks @tharakawj!

[gaearon]

We can get this in?

[Timer]

Yup, I didn't catch the switch to error.