Bug 1592658 - Policy should not override user's locale choice. r=jaws,zbraniecki

Differential Revision: https://phabricator.services.mozilla.com/D79913

browser/components/enterprisepolicies/Policies.jsm

@@ -1456,13 +1456,21 @@ var Policies = {
 
   RequestedLocales: {
     onBeforeAddons(manager, param) {
+      let requestedLocales;
       if (Array.isArray(param)) {
-        Services.locale.requestedLocales = param;
+        requestedLocales = param;
       } else if (param) {
-        Services.locale.requestedLocales = param.split(",");
+        requestedLocales = param.split(",");
       } else {
-        Services.locale.requestedLocales = [];
+        requestedLocales = [];
       }
+      runOncePerModification(
+        "requestedLocales",
+        JSON.stringify(requestedLocales),
+        () => {
+          Services.locale.requestedLocales = requestedLocales;
+        }
+      );
     },
   },
 

browser/components/enterprisepolicies/tests/xpcshell/test_requestedlocales.js

@@ -3,6 +3,8 @@
 
 "use strict";
 
+var { setTimeout } = ChromeUtils.import("resource://gre/modules/Timer.jsm");
+
 const REQ_LOC_CHANGE_EVENT = "intl:requested-locales-changed";
 
 function promiseLocaleChanged(requestedLocale) {
@@ -22,6 +24,27 @@ function promiseLocaleChanged(requestedLocale) {
   });
 }
 
+function promiseLocaleNotChanged(requestedLocale) {
+  return new Promise(resolve => {
+    let localeObserver = {
+      observe(aSubject, aTopic, aData) {
+        switch (aTopic) {
+          case REQ_LOC_CHANGE_EVENT:
+            ok(false, "Locale should not change.");
+            Services.obs.removeObserver(localeObserver, REQ_LOC_CHANGE_EVENT);
+            resolve();
+        }
+      },
+    };
+    Services.obs.addObserver(localeObserver, REQ_LOC_CHANGE_EVENT);
+    /* eslint-disable mozilla/no-arbitrary-setTimeout */
+    setTimeout(function() {
+      Services.obs.removeObserver(localeObserver, REQ_LOC_CHANGE_EVENT);
+      resolve();
+    }, 100);
+  });
+}
+
 add_task(async function test_requested_locale_array() {
   let originalLocales = Services.locale.requestedLocales;
   let localePromise = promiseLocaleChanged("de");
@@ -66,3 +89,29 @@ add_task(async function test_system_locale_string() {
   await localePromise;
   Services.locale.requestedLocales = originalLocales;
 });
+
+add_task(async function test_user_requested_locale_change() {
+  let originalLocales = Services.locale.requestedLocales;
+  let localePromise = promiseLocaleChanged("fr");
+  await setupPolicyEngineWithJson({
+    policies: {
+      RequestedLocales: "fr",
+    },
+  });
+  await localePromise;
+
+  // Simulate user change of locale
+  localePromise = promiseLocaleChanged("de");
+  Services.locale.requestedLocales = ["de"];
+  await localePromise;
+
+  localePromise = promiseLocaleNotChanged("fr");
+  await setupPolicyEngineWithJson({
+    policies: {
+      RequestedLocales: "fr",
+    },
+  });
+  await localePromise;
+
+  Services.locale.requestedLocales = originalLocales;
+});