fix(build): respect rollup output.assetFileNames, fix #2944

[SegaraRai]

Description

Fixes #2944.
This PR is a continuation of #2957.

I don't know if it's ok to create a continuation of someone's work, so please close this if it is invalid.

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[patak-dev]

Thanks for the PR @SegaraRai, it is ok to continue the work of others if it got stale. No problem.

We should also move the 233-300 block to a new function at the end of this file, so the main function is easier to follow. And we can replace the naming of vars like _extname to extname there.

[SegaraRai]

Thanks for the review.
Fixed the code.

BTW, I think I should write some tests, but I couldn't figure out how to write tests with multiple vite.config.js...

[Shinigami92]

As you mentioned, beside of missing test, LGTM

[patak-dev]

There were some tests added here #4122 for plugin-legacy, but I don't think that this is the best way to test it. We now have 404 in that playground for example. IMO we need a better way to add this to the test suite. We could do it in another PR also, maybe changing some of the playgrounds (like the asset one) to use the function type and return different patterns and then check that the files were properly generated? We could also add unit tests for the new fileAssetsNameToFileName function (check out other __tests__ folders in src)

[SegaraRai]

Thanks. I've added some unit tests.
I'm sorry but the test using vite.config.js was bit difficult for me, so I'm going to give up adding it.

[jbruni]

👀 Expecting this to be released.

Thank you.

[JR93]

It still does not work when I use the plugin @vitejs/plugin-Legacy. The plugin seems to add an output config, so the output option is an array type, then I always get the defaults value.

const output = config.build?.rollupOptions?.output
const assetFileNames =
  (output && !Array.isArray(output) ? output.assetFileNames : undefined) ??
  // defaults to '<assetsDir>/[name].[hash][extname]'
  // slightly different from rollup's one ('assets/[name]-[hash][extname]')
  path.posix.join(config.build.assetsDir, '[name].[hash][extname]')

[SegaraRai]

output of array form is currently not supported because it is not clear which one to use.
This could be fixed in another PR if there is an appropriate logic...

[patak-dev]

Yes, @JR93 please open a new issue with a minimal reproduction so the logic can be discussed there. Thanks!