1 files changed, 114 insertions, 0 deletions
diff --git a/toolkit/components/translations/tests/browser/browser_translations_lang_tags.js b/toolkit/components/translations/tests/browser/browser_translations_lang_tags.js
new file mode 100644
index 0000000000..3540df0beb
--- /dev/null
+++ b/toolkit/components/translations/tests/browser/browser_translations_lang_tags.js
@@ -0,0 +1,114 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+async function runLangTagsTest(
+  {
+    systemLocales,
+    appLocales,
+    webLanguages,
+    page,
+    languagePairs = LANGUAGE_PAIRS,
+  },
+  langTags
+) {
+  const cleanupLocales = await mockLocales({
+    systemLocales,
+    appLocales,
+    webLanguages,
+  });
+
+  const { cleanup: cleanupTestPage } = await loadTestPage({
+    page,
+    languagePairs,
+  });
+  const actor = getTranslationsParent();
+
+  await waitForCondition(
+    async () => actor.languageState.detectedLanguages?.docLangTag,
+    "Waiting for a document language tag to be found."
+  );
+
+  Assert.deepEqual(actor.languageState.detectedLanguages, langTags);
+
+  await cleanupLocales();
+  await cleanupTestPage();
+}
+
+add_task(async function test_lang_tags_direct_translations() {
+  info(
+    "Test the detected languages for translations when a translation pair is available"
+  );
+  await runLangTagsTest(
+    {
+      systemLocales: ["en"],
+      appLocales: ["en"],
+      webLanguages: ["en"],
+      page: SPANISH_PAGE_URL,
+    },
+    {
+      docLangTag: "es",
+      userLangTag: "en",
+      isDocLangTagSupported: true,
+    }
+  );
+});
+
+add_task(async function test_lang_tags_with_pivots() {
+  info("Test the detected languages for translations when a pivot is needed.");
+  await runLangTagsTest(
+    {
+      systemLocales: ["fr"],
+      appLocales: ["fr", "en"],
+      webLanguages: ["fr", "en"],
+      page: SPANISH_PAGE_URL,
+    },
+    {
+      docLangTag: "es",
+      userLangTag: "fr",
+      isDocLangTagSupported: true,
+    }
+  );
+});
+
+add_task(async function test_lang_tags_with_pivots_second_preferred() {
+  info(
+    "Test using a pivot language when the first preferred lang tag doesn't match"
+  );
+  await runLangTagsTest(
+    {
+      systemLocales: ["it"],
+      appLocales: ["it", "en"],
+      webLanguages: ["it", "en"],
+      page: SPANISH_PAGE_URL,
+    },
+    {
+      docLangTag: "es",
+      userLangTag: "en",
+      isDocLangTagSupported: true,
+    }
+  );
+});
+
+add_task(async function test_lang_tags_with_non_supported_doc_language() {
+  info("Test using a pivot language when the doc language isn't supported");
+  await runLangTagsTest(
+    {
+      systemLocales: ["fr"],
+      appLocales: ["fr", "en"],
+      webLanguages: ["fr", "en"],
+      page: SPANISH_PAGE_URL,
+      languagePairs: [
+        { fromLang: PIVOT_LANGUAGE, toLang: "fr" },
+        { fromLang: "fr", toLang: PIVOT_LANGUAGE },
+        // No Spanish support.
+      ],
+    },
+    {
+      docLangTag: "es",
+      userLangTag: "fr",
+      isDocLangTagSupported: false,
+    }
+  );
+});