build(common): specify explicit locales dir in package.json (#21016)

PR Close #21016

integration/i18n/package.json

@@ -24,7 +24,8 @@
   "scripts": {
     "postinstall": "webdriver-manager update --gecko false --standalone false $CHROMEDRIVER_VERSION_ARG",
     "closure": "java -jar node_modules/google-closure-compiler/compiler.jar --flagfile closure.conf",
-    "test": "ngc && yarn run closure && concurrently \"yarn run serve\" \"yarn run protractor\" --kill-others --success first",
+    "test": "ngc && yarn run closure && concurrently \"yarn run serve\" \"yarn run protractor\" --kill-others --success first && npm run test-locale-folder",
+    "test-locale-folder": "node test-locale-folder.js",
     "serve": "lite-server -c e2e/browser.config.json",
     "preprotractor": "tsc -p e2e",
     "protractor": "protractor e2e/protractor.config.js"

integration/i18n/test-locale-folder.js

@@ -0,0 +1,14 @@
+const fs = require('fs');
+const path = require('path');
+
+const packageJson = require('@angular/common/package.json');
+const localesFolder = packageJson['locales'];
+if (!localesFolder) {
+  throw new Error(`@angular/common/package.json does not contain 'locales' entry.`)
+}
+const enLocalePath = `@angular/common/${localesFolder}/en`;
+try {
+  require.resolve(enLocalePath);
+} catch (err) {
+  throw new Error(`@angular/common does not contain 'en' locale in ${enLocalePath}.`)
+}

packages/common/package.json

@@ -11,6 +11,7 @@
   "dependencies": {
     "tslib": "^1.7.1"
   },
+  "locales": "locales",
   "peerDependencies": {
     "rxjs": "^5.5.0",
     "@angular/core": "0.0.0-PLACEHOLDER"