Typing regression on "useI18n()": spyOn return "never" type

[pinguet62]

Reporting a bug?

After upgrade from 9.3.0-beta.27, the mock of useI18n() doesn't work:

import * as vueI18n from 'vue-i18n'

vi.spyOn(vueI18n, 'useI18n').mockReturnValue({})

throws
Property 'mockReturnValue' does not exist on type 'never'.

Expected behavior

No error :)

Reproduction

1. Create TypeScript project
2. npm install vue-i118n
3. Add a simple test

   import { vi } from 'vitest'
   import * as vueI18n from 'vue-i18n'
   vi.spyOn(vueI18n, 'useI18n').mockReturnValue({})

4. npm run type-check

System Info

System:
    OS: Windows 10 10.0.22621
    CPU: (20) x64 12th Gen Intel(R) Core(TM) i7-12800H
    Memory: 10.91 GB / 31.69 GB
  Binaries:
    Node: 20.0.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.19 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 9.8.1 - C:\Program Files\nodejs\npm.CMD
    pnpm: 8.5.0 - ~\AppData\Roaming\npm\pnpm.CMD
  Browsers:
    Edge: Spartan (44.22621.2134.0), Chromium (117.0.2045.36)
    Internet Explorer: 11.0.22621.1

Screenshot

No response

Additional context

Seems be a regression in #1309 7ebb0e4#diff-90783ef144f3a897c890355ff61bd08a99bbd36764128426b6f899a72e766f2eR803

Reverting line to previous version NonNullable<Options['locale']> seems fix the problem.
Like the test:type checks are still OK, probably the current typing is too strict? 🤔

Validations

• Read the Contributing Guidelines
• Read the Documentation
• 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 Discussions

[github-actions]

Would you be able to provide a reproduction 🙏

More info

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How can I create a reproduction?

We have a couple of templates for starting with a minimal reproduction:

👉 Reproduction mininal starter
👉 Reproduction starter with unpluguin-vue-i18n

A public GitHub repository is also perfect. 👌

Please ensure that the reproduction is as minimal as possible.

You might also find these other articles interesting and/or helpful:

• The Importance of Reproductions
• How to Generate a Minimal, Complete, and Verifiable Example

[pinguet62]

I created a repo with minimal configuration
ℹ️ 1 commit == 1 CLI command

git clone git@github.com:pinguet62/vue-i18n--typing-regression.git
cd vue-i18n--typing-regression
npm ci
npm run type-check

> vue-i18n--typing-regression@0.0.0 type-check
> vue-tsc --noEmit -p tsconfig.vitest.json --composite false

src/sample.spec.ts:8:38 - error TS2339: Property 'mockReturnValue' does not exist on type 'never'.

8         vi.spyOn(vueI18n, 'useI18n').mockReturnValue({
                                       ~~~~~~~~~~~~~~~


Found 1 error in src/sample.spec.ts:8


Process finished with exit code 2

[pinguet62]

🖖 Any news?