1 files changed, 20 insertions, 0 deletions
diff --git a/js/src/tests/Intl/four-letter-language-codes.js b/js/src/tests/Intl/four-letter-language-codes.js
new file mode 100644
index 000000000..b92b4c3e1
--- /dev/null
+++ b/js/src/tests/Intl/four-letter-language-codes.js
@@ -0,0 +1,20 @@
+// |reftest| skip-if(!this.hasOwnProperty("Intl"))
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// So many non-existent four letter language codes to pick from.
+const languageTags = {
+    "Flob": "flob",
+    "ZORK": "zork",
+    "Blah-latn": "blah-Latn",
+    "QuuX-latn-us": "quux-Latn-US",
+    "SPAM-gb-x-Sausages-BACON-eggs": "spam-GB-x-sausages-bacon-eggs",
+};
+
+for (let [tag, canonical] of Object.entries(languageTags)) {
+    assertEq(Intl.getCanonicalLocales(tag)[0], canonical);
+}
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);