1 files changed, 61 insertions, 0 deletions
diff --git a/js/src/tests/non262/Intl/Locale/likely-subtags.js b/js/src/tests/non262/Intl/Locale/likely-subtags.js
new file mode 100644
index 0000000000..3b3e4bd905
--- /dev/null
+++ b/js/src/tests/non262/Intl/Locale/likely-subtags.js
@@ -0,0 +1,61 @@
+// |reftest| skip-if(!this.hasOwnProperty('Intl'))
+
+var testDataMaximal = {
+    // Keeps "und" primary language.
+    "und-AQ": "und-Latn-AQ",
+
+    // Modifies primary language.
+    "und-Cyrl-RO": "bg-Cyrl-RO",
+}
+
+var testDataMinimal = {
+    // Undefined primary language.
+    "und": "en",
+    "und-Thai": "th",
+    "und-419": "es-419",
+    "und-150": "ru",
+    "und-AT": "de-AT",
+
+    // https://ssl.icu-project.org/trac/ticket/13786
+    "aae-Latn-IT": "aae",
+    "aae-Thai-CO": "aae-Thai-CO",
+
+    // https://ssl.icu-project.org/trac/ticket/10220
+    // https://ssl.icu-project.org/trac/ticket/12345
+    "und-CW": "pap",
+    "und-US": "en",
+    "zh-Hant": "zh-TW",
+    "zh-Hani": "zh-Hani",
+};
+
+// Add variants, extensions, and privateuse subtags and ensure they don't
+// modify the result of the likely subtags algorithms.
+var extras = [
+    "fonipa",
+    "a-not-assigned",
+    "u-attr",
+    "u-co",
+    "u-co-phonebk",
+    "x-private",
+];
+
+for (var [tag, maximal] of Object.entries(testDataMaximal)) {
+    assertEq(new Intl.Locale(tag).maximize().toString(), maximal);
+    assertEq(new Intl.Locale(maximal).maximize().toString(), maximal);
+
+    for (var extra of extras) {
+        assertEq(new Intl.Locale(tag + "-" + extra).maximize().toString(), maximal + "-" + extra);
+    }
+}
+
+for (var [tag, minimal] of Object.entries(testDataMinimal)) {
+    assertEq(new Intl.Locale(tag).minimize().toString(), minimal);
+    assertEq(new Intl.Locale(minimal).minimize().toString(), minimal);
+
+    for (var extra of extras) {
+        assertEq(new Intl.Locale(tag + "-" + extra).minimize().toString(), minimal + "-" + extra);
+    }
+}
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);