test: add installModule options tests

specs/basic_usage.spec.ts

@@ -617,4 +617,11 @@ describe('basic usage', async () => {
     expect(dom.querySelector('head #switch-locale-path').content).toEqual('/fr/composables')
     expect(dom.querySelector('head #route-base-name').content).toEqual('nested-test-route')
   })
+
+  test('(#2874) options `locales` and `vueI18n` passed using `installModule` are not overridden', async () => {
+    const { page } = await renderPage('/')
+
+    expect(await getText(page, '#install-module-locale')).toEqual('Installer module locale works!')
+    expect(await getText(page, '#install-module-vue-i18n')).toEqual('Installer module vue-i18n works!')
+  })
 })

specs/fixtures/basic_usage/installer-module/i18n.config.ts

@@ -0,0 +1,9 @@
+import type { I18nOptions } from 'vue-i18n'
+
+export default {
+  messages: {
+    en: {
+      installerModuleVueI18nMessage: 'Installer module vue-i18n works!'
+    }
+  }
+} as I18nOptions

specs/fixtures/basic_usage/installer-module/index.ts

@@ -0,0 +1,20 @@
+import { createResolver, defineNuxtModule, installModule } from '@nuxt/kit'
+
+export default defineNuxtModule({
+  async setup(options, nuxt) {
+    const { resolve } = createResolver(import.meta.url)
+
+    installModule('@nuxtjs/i18n', {
+      langDir: resolve('./locales'),
+      vueI18n: resolve('./i18n.config.ts'),
+      locales: [
+        {
+          code: 'en',
+          iso: 'en-US',
+          files: [resolve('./locales/en.json')],
+          name: 'English'
+        }
+      ]
+    })
+  }
+})

specs/fixtures/basic_usage/installer-module/locales/en.json

@@ -0,0 +1,3 @@
+{
+  "installerModuleLocaleMessage": "Installer module locale works!"
+}

specs/fixtures/basic_usage/nuxt.config.ts

@@ -1,7 +1,7 @@
 // https://nuxt.com/docs/guide/directory-structure/nuxt.config
 export default defineNuxtConfig({
   devtools: { enabled: true },
-  modules: ['./layer-module', '@nuxtjs/i18n'],
+  modules: ['./layer-module', './installer-module', '@nuxtjs/i18n'],
   runtimeConfig: {
     public: {
       runtimeValue: 'Hello from runtime config!',

specs/fixtures/basic_usage/pages/index.vue

@@ -239,5 +239,9 @@ useHead({
       <code id="global-scope-properties">{{ localeProperties }}</code>
       <LocalScope />
     </section>
+    <section>
+      <div id="install-module-locale">{{ $t('installerModuleLocaleMessage') }}</div>
+      <div id="install-module-vue-i18n">{{ $t('installerModuleVueI18nMessage') }}</div>
+    </section>
   </div>
 </template>