How mock i18n with vitest

[fchancel]

Hello,

I've been fighting for a day about the i18n mock with vitest.
Before updating to v9, I make a global mock as follows in vitest.setup.ts

vi.mock("vue-i18n", () => ({
  useI18n: () => ({
    t: (key: string) => key,
    locale: ref("en"),
  }),

  createI18n: () => ({
    install: () => {},
  }),
}));

But since the update, I've tried a number of solutions to make an i18n mock, but I've never succeeded.
I keep getting the following error:

SyntaxError: Need to install with `app.use` function
 ❯ Module.createCompileError ../node_modules/@intlify/message-compiler/dist/message-compiler.mjs:78:19
     76|         : code;
     77|     const error = new SyntaxError(String(msg));
     78|     error.code = code;
       |                   ^
     79|     if (loc) {
     80|         error.location = loc;
 ❯ createI18nError ../node_modules/vue-i18n/dist/vue-i18n.mjs:81:34
 ❯ Module.useI18n ../node_modules/vue-i18n/dist/vue-i18n.mjs:2187:15
 ❯ setup modules/test/pages/test/test.vue:28:19
 ❯ wrappedSetup ../node_modules/@nuxt/test-utils/dist/runtime-utils/index.mjs:244:28
 ❯ clonedComponent.setup ../node_modules/@nuxt/test-utils/dist/runtime-utils/index.mjs:328:50
 ❯ callWithErrorHandling ../node_modules/@vue/runtime-core/dist/runtime-core.cjs.js:200:19
 ❯ setupStatefulComponent ../node_modules/@vue/runtime-core/dist/runtime-core.cjs.js:7848:25
 ❯ setupComponent ../node_modules/@vue/runtime-core/dist/runtime-core.cjs.js:7809:36
 ❯ mountComponent ../node_modules/@vue/runtime-core/dist/runtime-core.cjs.js:5159:7

knowing that in my component view. I use the following format:

const { t } = useI18n()

and that my nuxt.config.ts is

is as follows:

  i18n: {
    strategy: "no_prefix",
    locales: [
      {
        code: "en",
        name: "English",
        files: ["en.json"],
      },
      {
        code: "fr",
        name: "Français",
        files: ["fr.json"],
      },
    ],
    defaultLocale: "en",
    detectBrowserLanguage: {
      useCookie: true,
      cookieKey: "i18n_test",
      fallbackLocale: "en",
    },
  },

Do you have any solutions ?

[th1nkgr33n]

Although I got another issues with the new Update :D

In the past we have configured a global i18n mock/instance in the setup.ts file of vitest.
Currently this throws a duplicated init warning for the t function, but if I remove this, I got your error, so this might help?

// https://github.com/nuxt/test-utils/issues/566#issuecomment-2200984889
import { config } from '@vue/test-utils'
import { createI18n } from 'vue-i18n'

const i18n = createI18n({
  legacy: false,
  globalInjection: true,
  locale: 'de',
  missing: (_, key) => key,
})

config.global.plugins.push(i18n)

vue-i18n made the use of the useI18n composable much stricter, not to use it outside of a
For other purposes you need to use useNuxtApp().$i18n