Use chunk.forEachModules instead of deprecated chunk.modules

[janicduplessis]

What did you implement:

Webpack 4 removes the deprecated chunk.modules property. This uses the forEachModule instead. See https://github.com/webpack/webpack/blob/webpack-3/lib/Chunk.js#L473.

forEachModule exists since webpack v3 so this means webpack v2 is no longer supported with this change. Not sure how much we care about webpack 2 support. If we want we could check if forEachModule exists and fallback to .modules.

How did you implement it:

Trivial, most changes were to update tests.

How can we verify it:

• Tested in a project using webpack 4, before this change externals were broken.
• Run tests

Todos:

• Write tests (N/A)
• Write documentation (N/A)
• Fix linting errors
• Make sure code coverage hasn't dropped
• Provide verification config / commands / resources
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES
Is it a breaking change?: YES (if webpack 2 is still supported)

[HyperBrain]

Hi @janicduplessis, thanks for the PR. It indeed makes sense to switch to the no-deprecated chunk module enumerator.

Regarding webpack 2 support, I think there are a lot of serverless projects out there that make use of it. Either we schedule this change for [email protected] and drop webpack 2 support completely or we implement a fallback mechanism.

However, I'd prefer a new major version, because as the old functionality is deprecated, it is much cleaner to continue with only the correct implementation and drop webpack 2 support.

[janicduplessis]

@HyperBrain I also think scheduling this for 5.0.0 is better. It would add support for webpack@4 and drop webpack@2.

[HyperBrain]

I retargeted this PR to the new v5 branch. According to #331 this is urgently needed to support webpack v4, so we'll prepare the v5 branch to gather everything needed to support it.

@janicduplessis Did you try already, if this PR enabled webpack 4 support?

[HyperBrain]

Tested in a project using webpack 4, before this change externals were broken.

Sorry 😄 . Did not read that.
The PR looks good to me, so I'll merge it into the v5 branch now.

[HyperBrain]

Released with 5.0.0