🐛 BUG: require('debug') resolves to @cloudflare/vitest-pool-workers/dist/worker/lib/debug.mjs instead of to the correct file

[hansottowirtz]

Which Cloudflare product(s) does this pertain to?

Workers Vitest Integration

What version(s) of the tool(s) are you using?

0.4.17

What version of Node are you using?

20

What operating system and version are you using?

macOS Sonoma 14.5

Describe the Bug

Observed behavior

When importing knex, a CJS module importing debug, an error is thrown: Cannot use require() to import an ES Module.
This is because require('debug') resolves to @cloudflare/vitest-pool-workers/dist/worker/lib/debug.mjs, due to these lines:

workers-sdk/packages/vitest-pool-workers/src/pool/module-fallback.ts

Lines 318 to 337 in eb6f249

	// `workerd` will always try to resolve modules relative to the referencing
	// dir first. Built-in `node:*`/`cloudflare:*` imports only exist at the root.
	// We need to ensure we only load a single copy of these modules, therefore,
	// we return a redirect to the root here. Note `workerd` will automatically
	// look in the root if we return 404 from the fallback service when
	// *import*ing `node:*`/`cloudflare:*` modules, but not when *require()*ing
	// them. For the sake of consistency (and a nice return type on this function)
	// we return a redirect for `import`s too.
	if (referrerDir !== "/" && workerdBuiltinModules.has(specifier)) {
	return `/${specifier}`;
	}
	const specifierLibPath = posixPath.join(
	libPath,
	specifier.replaceAll(":", "/")
	);
	filePath = maybeGetTargetFilePath(specifierLibPath);
	if (filePath !== undefined) {
	return filePath;
	}

This results in a redirect:

VITEST-POOL-WORKERS:MODULE-FALLBACK 24525: require("<root>/node_modules/knex/lib/debug") relative to <root>/node_modules/knex/lib/client.js?mf_vitest_no_cjs_esm_shim: redirect: <root>/node_modules/@cloudflare/vitest-pool-workers/dist/worker/lib/debug.mjs?mf_vitest_no_cjs_esm_shim

Expected behavior

The file should resolve to the correct module.

Steps to reproduce

Make a worker with import Knex from "knex", and use it in a Vitest test.

Please provide a link to a minimal reproduction

https://github.com/hansottowirtz/workers-sdk-require-debug-repro

Please provide any relevant error logs

No response

[edmundhung]

We have just added Vite dependency pre-bundling support on v0.6.14 that should help resolving this issue.

For example, you can get ext-dep working with the following config:

export default defineWorkersConfig({
  test: {
    deps: {
      optimizer: {
        ssr: {
          enabled: true,
          include: ["ext-dep"],
        },
      },
    },
    poolOptions: {
      workers: {
        // ...
      },
    },
  },
});