feat: back-port from vue-i18n-next

.github/workflows/test.yml

@@ -40,3 +40,5 @@ jobs:
         run: pnpm install
       - name: Test
         run: pnpm test
+      # https://github.com/actions/runner/issues/795
+      - run: echo "NODE_ICU_DATA=" >> $GITHUB_ENV

limitation.md

@@ -0,0 +1,5 @@
+# Limitations
+- `createI18n` is singleton instance
+
+# TODOs
+- postTranslation I/F miss-match (cannot pass the key)

package.json

@@ -22,15 +22,19 @@
   },
   "devDependencies": {
     "@antfu/eslint-config-ts": "^0.6.6",
+    "@intlify/vue-i18n-core": "^9.2.0-beta.5",
     "@kazupon/lerna-changelog": "^4.3.0",
     "@secretlint/secretlint-rule-preset-recommend": "^3.1.0",
     "@types/jest": "^27.0.1",
     "@vue/composition-api": "^1.1.4",
     "@vue/test-utils": "^1.2.2",
     "@vue/vue2-jest": "^27.0.0-alpha.1",
+    "babel-jest": "^27.2.0",
+    "cross-env": "^7.0.3",
     "eslint": "^7.32.0",
     "eslint-config-prettier": "^8.3.0",
     "eslint-plugin-prettier": "^4.0.0",
+    "full-icu": "^1.3.1",
     "jest": "^27.1.1",
     "lint-staged": "^11.1.2",
     "npm-run-all": "^4.1.5",
@@ -105,8 +109,11 @@
     "release:trigger": "shipjs trigger",
     "test": "npm run test:cover",
     "test:cover": "npm run test:unit -- --coverage",
-    "test:unit": "jest --clearCache && jest --env node"
+    "test:unit": "jest --clearCache && cross-env NODE_ICU_DATA=./node_modules/full-icu jest --env node"
   },
   "sideEffects": false,
-  "types": "dist/index.d.ts"
+  "types": "dist/index.d.ts",
+  "dependencies": {
+    "@intlify/shared": "^9.2.0-beta.4"
+  }
 }