[robingenz]

Fixes #12984.
Fixes #13037.

On Vite 8, a require() in a CommonJS dependency resolved to the import entry of packages that ship both an import and a require entry. CommonJS code then got an ES module. With pg, for example, tests fail with SyntaxError: Cannot use import statement outside a module.

Why

viteResolve() in the module fallback service told Vite about a require() only through custom: { "node-resolve": { isRequire } }. Vite 7's resolve plugin reads that hint. Vite 8 uses rolldown's native viteResolvePlugin instead, and nothing reads the hint anymore. The native plugin picks require or import from the kind of each call. We passed no kind, so every lookup counted as an import.

Before rolldown 1.2.1, a kind passed from JS never reached the native plugin (rolldown/rolldown#10403). That is why #13062 had to rescan the exports map after resolution. rolldown/rolldown#10440 fixed this in rolldown 1.2.1, and Vite 8.3.0 and later require rolldown ~1.2.6. So passing kind is now enough, and the resolver does the work itself.

What

• viteResolve() passes kind: "require-call" for a require() and kind: "import-statement" for an import.
• It keeps custom["node-resolve"] for Vite 7 and earlier.
• It calls vite.environments.ssr.pluginContainer.resolveId() instead of vite.pluginContainer.resolveId(..., { ssr: true }). Both reach the same container. The server-level pluginContainer forwards kind at runtime, but its type has no kind field, so the environment's container keeps this typed.

Vite 8 releases with rolldown older than 1.2.1 (8.0 and 8.1) stay affected. Updating Vite fixes them.

Test

• New test in test/cjs-require.test.ts: a CommonJS package requires a dual-format package (import → index.mjs, require → index.cjs). The test expects the require entry. Without the fix it fails with expected 'esm' to be 'cjs'.
• The fake Vite servers in test/module-fallback.test.ts now stub environments.ssr.pluginContainer. All 37 tests in that file pass.
• I also applied the change to the built 1.4.0 package and ran a pg repro (the one in Vite 8 breaks importing pg in Vitest #12984). It fails before and passes after on Vite 8.3.0 and 8.3.4 with Vitest 4.1.11 and 5.0.3. It passes before and after on Vite 7.3.7.

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because: bug fix that restores the Vite 7 behaviour

🤖 Generated with Claude Code

---

[changeset-bot]

🦋 Changeset detected

Latest commit: 9c44bf8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@cloudflare/vitest-plugin	Patch

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[workers-devprod]

Codeowners approval required for this PR:

• @cloudflare/wrangler

Show detailed file reviewers

• .changeset/vitest-plugin-require-condition.md: [@cloudflare/wrangler]
• packages/vitest-plugin/src/pool/module-fallback.ts: [@cloudflare/wrangler]
• packages/vitest-plugin/test/cjs-require.test.ts: [@cloudflare/wrangler]
• packages/vitest-plugin/test/module-fallback.test.ts: [@cloudflare/wrangler]

[Copilot]

🟢 Approval recommended

The focused resolver fix preserves the legacy hint, includes regression coverage, and has no unresolved findings.

No open issues 🎉

What changed in this PR

Fixes CommonJS dependencies resolving to ESM exports on supported Vite 8 releases in the Workers Vitest integration.

Changes:

• Passes import kind through Vite’s SSR environment resolver while preserving the legacy resolution hint.
• Adds regression coverage and updates resolver stubs.
• Adds a patch changeset.

File	Description
packages/​vitest-plugin/​test/​module-fallback.test.ts	Updates stubs to use the SSR environment container.
packages/​vitest-plugin/​test/​cjs-require.test.ts	Tests CommonJS resolution of dual-format packages.
packages/​vitest-plugin/​src/​pool/​module-fallback.ts	Passes the require/import kind to Vite.
.changeset/​vitest-plugin-require-condition.md	Documents the resolution fix for release.

_{Review effort: Balanced}

[petebacondarwin]

OK let's re-open this and consider if it is the correct fix.

[clanky-the-clanker]

This pull request was not reviewed automatically because its author does not have write access to this repository. A maintainer with write access can start a review by commenting clanky review (or clanker review or @clanky-the-clanker review), optionally followed by instructions (e.g. clanky review focus on the retry logic).

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commit: 9c44bf8

[petebacondarwin]

clanker review

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Codeowners approval required for this PR:

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[petebacondarwin]

OK this LGTM.
Are we saying that this fix doesn't work on Vite 8.0.x, 8.1.x, and 8.2.0?
If so, I think we should mention that in the changeset.

[workers-devprod]

Codeowners reviews satisfied

[robingenz]

Yes. The fix needs rolldown 1.2.1 or later (rolldown/rolldown#10440), and Vite 8.2.1 is the first release that ships it. Vite 8.0.x, 8.1.x and 8.2.0 stay affected. I added that to the changeset and applied your suggestion.