fix: fix importOriginal with optimizer and query import

[davidhwilliams]

Description

• closes vi.mock importOriginal causes ERR_MODULE_NOT_FOUND with &v=<hash> suffix appended to path in 4.1.0 (regression from 4.0.x) #9887

original ocmment

Fxes a bug where removeQuery incorrectly strips out the leading ? parameter boundary symbol when purging internal runtime flags (like _vitest_original), leaving an orphaned & boundary behind. When a URL contains multiple query parameters (e.g., file.js?_vitest_original&v=12345), removing the first parameter results in an invalid string format (file.js&v=12345). The module evaluator subsequently treats the query parameter as a literal extension on disk, throwing an ERR_MODULE_NOT_FOUND runtime error.

This fix ensures that if a leading ? is stripped but subsequent & parameters remain, the first remaining ampersand is properly converted back into a ? query parameter delimiter.

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. If the feature is substantial or introduces breaking changes without a discussion, PR might be closed.
• Ideally, include a test that fails without this PR but passes with it.
• Please, don't make changes to pnpm-lock.yaml unless you introduce a new test example.
• Please check Allow edits by maintainers to make review process faster. Note that this option is not available for repositories that are owned by Github organizations.

Tests

• Run the tests with pnpm test:ci.

Documentation

• If you introduce new functionality, document it. You can run documentation with pnpm run docs command.

Changesets

• Changes in changelog are generated from PR name. Please, make sure that it explains your changes in an understandable manner. Please, prefix changeset messages with feat:, fix:, perf:, docs:, or chore:.

[netlify]

✅ Deploy Preview for vitest-dev ready!

Built without sensitive environment variables

Name	Link
🔨 Latest commit	61a30d6
🔍 Latest deploy log	https://app.netlify.com/projects/vitest-dev/deploys/6a20c6b727d07f0008d24fdb
😎 Deploy Preview	https://deploy-preview-10469--vitest-dev.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.
🤖 Make changes	Run an agent on this branch

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[hi-ogawa]

Please add integration test.

[davidhwilliams]

Hi @hi-ogawa, I'd be happy to add one

I couldn't find an existing test suite that directly covers this scenario or usage. Could you point me toward the preferred location for this integration test, along with maybe an example of a similar test you're looking for please? Thank you

[hi-ogawa]

For example, there's an integration test with optimzeDeps where we run fixture like this

vitest/test/e2e/test/optimize-deps.test.ts

Lines 7 to 10 in 46b8277

	const { errorTree, stderr } = await runVitest({
	root: './fixtures/optimize-deps',
	pool,
	})

vitest/test/e2e/fixtures/optimize-deps/vitest.config.ts

Lines 3 to 6 in 46b8277

	export default defineConfig({
	optimizeDeps: {
	include: ["@test/test-dep-url"],
	},

[davidhwilliams]

Added integration test. The test fails on the old code with the exact issue reported ERR_MODULE_NOT_FOUND and now passes with the fix

[hi-ogawa]

Can you test optmizeDeps scneario that reproduced the issue previously?

[davidhwilliams]

I apologize i misunderstood. I updated the optimizeDeps test suite to include a new test. This new test uses the same vitest.config as the others which includes using optimizeDeps.include and test.deps.optimizer.client which is the scenario thats specified in the original ticket.

The test uses vi.mock along with importOriginal which is also the scenario specified in the ticket. I confirmed the test does fail with the old code and pass with my changes.

I removed the other test i had added but i can add it back if you'd like though i think only one is necessary

[hi-ogawa]

It looks like Claude and Me hallucinated bad removeQuery in #9772. Now I ported the one from Vite that does handles the multiple queries properly.

[Copilot]

Pull request overview

Fixes a regression where importOriginal/vi.importActual could produce invalid module IDs when stripping Vitest’s internal _vitest_original flag from URLs that also include optimizer/version query parameters, leading to ERR_MODULE_NOT_FOUND (issue #9887).

Changes:

• Adjust removeQuery in the module runner to correctly remove _vitest_original without leaving malformed query separators.
• Add a unit test asserting importOriginal preserves query parameters (e.g. ?raw).
• Add an e2e fixture/test covering mocking behavior with SSR optimizer + (noExternal/external) dependency permutations.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/unit/test/mocking/import-actual-query.test.ts	New unit test ensuring importOriginal works with import IDs containing query (?raw).
test/unit/test/mocking/import-actual-query-target.ts	Target module used by the new unit test.
test/tsconfig.json	Adds vite/client types so query-suffixed imports (e.g. ?raw) typecheck in tests.
test/e2e/test/optimize-deps-mock.test.ts	New e2e test runner asserting the new optimize-deps mock fixture passes across pools.
test/e2e/package.json	Adds test-dep-simple2 to e2e workspace dependencies for the new fixture.
test/e2e/fixtures/optimize-deps-mock/vitest.config.ts	New fixture config exercising SSR optimizer behavior in the mocked-deps scenario.
test/e2e/fixtures/optimize-deps-mock/basic.test.ts	New fixture test mocking optimized + non-optimized deps and validating resolution behavior.
test/e2e/deps/dep-simple2/package.json	Adds a simple ESM dependency used by the new e2e fixture.
test/e2e/deps/dep-simple2/index.js	Implementation for test-dep-simple2.
pnpm-lock.yaml	Lockfile update for the new local e2e dependency.
packages/vitest/src/runtime/moduleRunner/utils.ts	Updates query manipulation logic used when stripping _vitest_original during module fetch.

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

[tomasz-megaport]

Thanks for fixing this! Would it be possible to backport to the 4.1.x line? This still reproduces on the latest published releases - vitest@4.1.8 and vitest@5.0.0-beta.4 (with vite@8.0.16), and it's pool-independent (threads/forks/vmThreads).

It blocks deps.optimizer + vi.mock(mod, async (importOriginal) => ({ ...await importOriginal() })) for any optimized dep (a common pattern for partially mocking a component library), with ERR_MODULE_NOT_FOUND on a malformed deps/<dep>.js&v=<hash> URL.

Minimal config that triggers it:

// vitest.config.ts
export default defineConfig({
  optimizeDeps: { include: ['@scope/ui'] },
  test: { deps: { optimizer: { client: { enabled: true, include: ['@scope/ui'] } } } },
})
// a spec doing: vi.mock('@scope/ui', async (io) => ({ ...await io(), x: vi.fn() })) -> ERR_MODULE_NOT_FOUND