Breakage in Node.js v20.6.0

[mcollina]

The new loader API in v20.6.0 broke esmock

   FAIL  "should return un-mocked file"
    Cannot find package '[object Object]?esmk=1' imported from /Users/matteo/Repositories/esmock/src/esmock.js

    at nextResolveCall (file:///Users/matteo/Repositories/esmock/src/esmockLoader.js:71:7)
    at resolve (file:///Users/matteo/Repositories/esmock/src/esmockLoader.js:78:12)

I did try a quick replacement with the new initialize, but it looked a bit harder than expected.

cc @GeoffreyBooth for visibility.

[koshic]

issue comes from here:

esmockModule -> moduleId, parent ../local/usesImportObjects.js file:///xxxxxx/esmock/tests/tests-node/esmock.node.global.test.js
esmockModule -> moduleFileURL {}
esmockModule -> moduleFileURL to string [object Object]

[koshic]

Another interesting point is nodejs/node#49028

"Unflags import.meta.resolve making the second parentURL argument still gated behind the same --experimental-import-meta-resolve flag so that existing users would retain backwards compatibility, while the default behaviour becomes standards compliant."

So we have 2 different behaviors of import.meta.resolve depending on experimental flag. And import.meta.resolve is always available.

I can successfully run a few tests with '--experimental-import-meta-resolve' and dirty patched resolve:

But there is a new error:

[iambumblehead]

I do have time to investigate a solution today. Feel free to give any suggestions that should be considered.

[iambumblehead]

@koshic thanks for finding the cause and writing the nice summary. I understand.

[koshic]

the native resolve function is broken in node 20.6

With --experimental-import-meta-resolve flag?

[koshic]

mkdir -p xxx && touch xxx/1.mjs && touch xxx/2.mjs && \
echo 'import {resolve} from "path"; console.log(import.meta.resolve("./1.mjs", "file://" + resolve("./xxx/2.mjs")))' > 3.mjs && \
node --experimental-import-meta-resolve 3.mjs

works as expected (== returns file URL for 1.mjs) in 20.5.0 & 20.6.0

[iambumblehead]

@koshic thanks eventually your solution will be used in this PR #236

[iambumblehead]

https://nodejs.org/api/esm.html#importmetaresolvespecifier

It seems import.meta.resolve will discontinue support for the 'parent' param, but indirectly continues support (for now) when the node process includes the flag --experimental-import-meta-resolve

Failing tests commented-out at the PR were caused by import.meta.resolve's lack of support for "parent". For example, this test does not resolve the eslint module relative to parent.

const fileURL = resolve.constructor.name === 'AsyncFunction'
    ? await resolve(id, parent) : resolve(id, parent)
// node v20.6, fileURL is incorrect, test fails
//  file:///home/bumble/software/esmock/node_modules/eslint/lib/api.js
// node v20.4, fileURL is correct, test passes
//  file:///home/bumble/software/esmock/tests/node_modules/eslint/lib/api.js

@koshic @mcollina what do you think? Maybe import.meta.resolve should be removed from esmock and the scripted resolvewithplus used instead. Most users are using resolvewithplus already anyway, because import.meta.resolve has been undefined without the experimental flag.

[iambumblehead]

Another issue affecting node v20.6: #237

The "load" hook is called with a nextLoad function that returns { source: null } for CJS modules in node v20.6

looping in @tommy-mitchell

[iambumblehead]

https://nodejs.org/api/esm.html#loadurl-context-nextload

The value of source can be omitted for type 'commonjs'. When a source is provided, all require calls from this module will be processed by the ESM loader with registered resolve and load hooks; [...] This behavior for nullish source is temporary — in the future, nullish source will not be supported.

[iambumblehead]

Based on investigation, node v20.6 partially allows the loader to process cjs trees imported at the global-CJS-imports test, however, unknown factors cause the process to fail when certain cjs trees are imported multiple times.

The failing test uses a package called "meow". Possibly, the meow package could be opened and dependency trees imported there disabled and enabled to learn more information about the problem.

[iambumblehead]

I think the problem is meow has a circular dependency