From 0855d540f3c84c10ff68ef9f84eba866e36df561 Mon Sep 17 00:00:00 2001
From: Erik Nordin <enordin@mozilla.com>
Date: Thu, 11 Apr 2024 15:55:30 +0000
Subject: [PATCH] Bug 1890897 - Fix FullPagePanel lang-list initialization
 r=translations-reviewers,gregtatum

Fixes an issue where the default "Choose a language"
menu item was accidentally being removed from the
FullPageTranslationsPanel menu lists.

Differential Revision: https://phabricator.services.mozilla.com/D207218
---
 .../translations/content/TranslationsPanelShared.sys.mjs   | 14 ++++++++++----
 ...rowser_translations_full_page_panel_unsupported_lang.js |  3 +++
 browser/components/translations/tests/browser/head.js      |  4 ++++
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/browser/components/translations/content/TranslationsPanelShared.sys.mjs b/browser/components/translations/content/TranslationsPanelShared.sys.mjs
index 48ea69dc3837..e43a18687b85 100644
--- a/browser/components/translations/content/TranslationsPanelShared.sys.mjs
+++ b/browser/components/translations/content/TranslationsPanelShared.sys.mjs
@@ -114,8 +114,14 @@ export class TranslationsPanelShared {
     );
 
     for (const popup of fromPopups) {
-      while (popup.firstChild) {
-        popup.firstChild.remove();
+      // For the moment, the FullPageTranslationsPanel includes its own
+      // menu item for "Choose another language" as the first item in the list
+      // with an empty-string for its value. The SelectTranslationsPanel has
+      // only languages in its list with BCP-47 tags for values. As such,
+      // this loop works for both panels, to remove all of the languages
+      // from the list, but ensuring that any empty-string items are retained.
+      while (popup.lastChild?.value) {
+        popup.lastChild.remove();
       }
       for (const { langTag, displayName } of fromLanguages) {
         const fromMenuItem = document.createXULElement("menuitem");
@@ -126,8 +132,8 @@ export class TranslationsPanelShared {
     }
 
     for (const popup of toPopups) {
-      while (popup.firstChild) {
-        popup.firstChild.remove();
+      while (popup.lastChild?.value) {
+        popup.lastChild.remove();
       }
       for (const { langTag, displayName } of toLanguages) {
         const toMenuItem = document.createXULElement("menuitem");
diff --git a/browser/components/translations/tests/browser/browser_translations_full_page_panel_unsupported_lang.js b/browser/components/translations/tests/browser/browser_translations_full_page_panel_unsupported_lang.js
index 21f7e8fdb780..59be1e329b39 100644
--- a/browser/components/translations/tests/browser/browser_translations_full_page_panel_unsupported_lang.js
+++ b/browser/components/translations/tests/browser/browser_translations_full_page_panel_unsupported_lang.js
@@ -23,6 +23,9 @@ add_task(async function test_unsupported_lang() {
   });
 
   await FullPageTranslationsTestUtils.clickChangeSourceLanguageButton();
+  FullPageTranslationsTestUtils.assertPanelViewDefault();
+  FullPageTranslationsTestUtils.assertSelectedFromLanguage({ langTag: "" });
+  FullPageTranslationsTestUtils.assertSelectedToLanguage({ langTag: "en" });
 
   await cleanup();
 });
diff --git a/browser/components/translations/tests/browser/head.js b/browser/components/translations/tests/browser/head.js
index ccc9ca54a3c5..81802b89ffa3 100644
--- a/browser/components/translations/tests/browser/head.js
+++ b/browser/components/translations/tests/browser/head.js
@@ -320,6 +320,10 @@ class SharedTranslationsTestUtils {
    * @param {string} [options.l10nId] - The localization Id to match.
    */
   static _assertSelectedLanguage(menuList, { langTag, l10nId }) {
+    ok(
+      menuList.label,
+      `The label for the menulist ${menuList.id} should not be empty.`
+    );
     if (langTag) {
       is(
         menuList.value,
-- 
2.11.4.GIT