vi.mock importOriginal is empty when vi.resetModules is used (since 4.1.0)

[Nico142]

Describe the bug

After updating Vitest from 4.0.18 to 4.1.0, importOriginal from vi.mock is empty when using resetModules and isolate: false.

I run my tests with maxWorkers: 1, isolate: false, and vi.resetModules(); in a beforeEach. When using importOriginal from vi.mock in setupTests.js, the first test suite runs successfully. However, the second test throws this error:

No "connect" export is defined on the "react-redux" mock. Did you forget to return it from "vi.mock"?
If you need to partially mock a module, you can use "importOriginal" helper inside:

When logging original, the first test suite logs all exports from react-redux, but the second suite logs this instead:

[Object: null prototype] [Module] {} 

Reproduction

// vitest.config.js

export default defineConfig({
  test: {
    setupFiles: ['./setupTests.js'],
    maxWorkers: 1,
    isolate: false,
  },
})

// setupTests.js

vi.mock('react-redux', async (importOriginal) => {
  const original = await importOriginal();

  return {
    ...original,
    useSelector: (callback) => callback(),
    useDispatch: () => (callback) => callback(),
  };
});

beforeEach(() => {
  vi.resetModules();
});

Here is a StackBlitz example, with Lodash instead of react-redux:
https://stackblitz.com/edit/vitest-dev-vitest-z5dhbqpm?file=package.json&view=editor

System Info

- Vite 7
- Vitest 4.1.0

Used Package Manager

npm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[hi-ogawa]

I think this behavior is "expected" since importOriginal's module is the original module which gets reset like any other normal modules, but I'm not sure if it's a "good" behavior. Perhaps something changed in #9774 or #9772.
(Or it's also possible it's broken before just like #9771)

---

Confirmed passes on 4.1.0-beta.5 and fails on 4.1.0-beta.6 https://github.com/vitest-dev/vitest/releases/tag/v4.1.0-beta.6, so that means #9774 and #9772 are relevant.

[hi-ogawa]

Found a single test reproduction https://stackblitz.com/edit/vitest-dev-vitest-rr7ugj6a?file=test%2Frepro.test.ts

import { test, vi } from "vitest"

test("repro", async () => {
  vi.doMock(import("vite"), async (importOriginal) => {
    const lib = await importOriginal();
    return lib;
  })

  const lib1: any = await import("vite")
  console.log("[lib1]", Object.keys(lib1).slice(0, 3)) // 👍 prints [ 'BuildEnvironment', 'DevEnvironment', 'build' ]

  vi.resetModules();
  vi.doMock(import("vite"), async (importOriginal) => {
    const lib = await importOriginal();
    return lib;
  })

  const lib2: any = await import("vite")
  console.log("[lib2]", Object.keys(lib2).slice(0, 3)) // 👎 prints empty 
})

This only happens when mocking external. This didn't reproduce in the following:

test('ok', async () => {
  vi.doMock(import("./repro.js"), async (importOriginal) => {
    const lib = await importOriginal();
    return lib;
  })

  const lib1: any = await import("./repro.js")
  console.log("[lib1]", Object.keys(lib1).slice(0, 3)) // 👍 prints

  vi.resetModules();
  vi.doMock(import("./repro.js"), async (importOriginal) => {
    const lib = await importOriginal();
    return lib;
  })

  const lib2: any = await import("./repro.js")
  console.log("[lib2]", Object.keys(lib2).slice(0, 3)) // 👍 prints
})

[psyvision]

@sheremet-va any ETA on when this may release please?

[andrewbrennanfr]

Confirmed passes on 4.1.0-beta.5 and fails on 4.1.0-beta.6

Yes this is a problem for us too. Checked with the above versions ☝️
On beta.6 we have a few 100 failing tests 😅

If you have an ETA on release it would be great.