1 files changed, 74 insertions, 0 deletions
diff --git a/js/src/tests/non262/Intl/extensions/unicode-extension-sequences.js b/js/src/tests/non262/Intl/extensions/unicode-extension-sequences.js
new file mode 100644
index 0000000000..ead69a4632
--- /dev/null
+++ b/js/src/tests/non262/Intl/extensions/unicode-extension-sequences.js
@@ -0,0 +1,74 @@
+// |reftest| skip-if(!this.getSelfHostedValue)
+
+const startOfUnicodeExtensions = getSelfHostedValue("startOfUnicodeExtensions");
+const endOfUnicodeExtensions = getSelfHostedValue("endOfUnicodeExtensions");
+
+const testcases = [
+    // Language tag without Unicode extension.
+    { locale: "en", start: -1, end: 0 },
+    { locale: "en-Latn", start: -1, end: 0 },
+    { locale: "en-x-y", start: -1, end: 0 },
+    { locale: "en-x-yz", start: -1, end: 0 },
+    { locale: "en-x-u-kf", start: -1, end: 0 },
+
+    // Unicode extension sequence starts with key subtag.
+    // - no suceeding key or type subtags.
+    { locale: "en-u-ab", start: 2, end: 7 },
+    { locale: "en-u-ab-x-y", start: 2, end: 7 },
+    { locale: "en-u-ab-x-yz", start: 2, end: 7 },
+    { locale: "en-u-ab-x-u-kn", start: 2, end: 7 },
+    // - followed by key subtag.
+    { locale: "en-u-ab-cd", start: 2, end: 10 },
+    { locale: "en-u-ab-cd-x-y", start: 2, end: 10 },
+    { locale: "en-u-ab-cd-x-yz", start: 2, end: 10 },
+    { locale: "en-u-ab-cd-x-u-kn", start: 2, end: 10 },
+    // - followed by type subtag.
+    { locale: "en-u-ab-cdef", start: 2, end: 12 },
+    { locale: "en-u-ab-cdef-x-y", start: 2, end: 12 },
+    { locale: "en-u-ab-cdef-x-yz", start: 2, end: 12 },
+    { locale: "en-u-ab-cdef-x-y-u-kn", start: 2, end: 12 },
+
+    // Unicode extension sequence starts with attribute subtag.
+    // - no suceeding attribute or key subtags.
+    { locale: "en-u-abc", start: 2, end: 8 },
+    { locale: "en-u-abc-x-y", start: 2, end: 8 },
+    { locale: "en-u-abc-x-yz", start: 2, end: 8 },
+    { locale: "en-u-abc-x-y-u-kn", start: 2, end: 8 },
+    // - followed by attribute subtag.
+    { locale: "en-u-abc-def", start: 2, end: 12 },
+    { locale: "en-u-abc-def-x-y", start: 2, end: 12 },
+    { locale: "en-u-abc-def-x-yz", start: 2, end: 12 },
+    { locale: "en-u-abc-def-x-y-u-kn", start: 2, end: 12 },
+    // - followed by key subtag.
+    { locale: "en-u-abc-de", start: 2, end: 11 },
+    { locale: "en-u-abc-de-x-y", start: 2, end: 11 },
+    { locale: "en-u-abc-de-x-yz", start: 2, end: 11 },
+    { locale: "en-u-abc-de-x-y-u-kn", start: 2, end: 11 },
+    // - followed by two key subtags.
+    { locale: "en-u-abc-de-fg", start: 2, end: 14 },
+    { locale: "en-u-abc-de-fg-x-y", start: 2, end: 14 },
+    { locale: "en-u-abc-de-fg-x-yz", start: 2, end: 14 },
+    { locale: "en-u-abc-de-fg-x-y-u-kn", start: 2, end: 14 },
+    // - followed by key and type subtag.
+    { locale: "en-u-abc-de-fgh", start: 2, end: 15 },
+    { locale: "en-u-abc-de-fgh-x-y", start: 2, end: 15 },
+    { locale: "en-u-abc-de-fgh-x-yz", start: 2, end: 15 },
+    { locale: "en-u-abc-de-fgh-x-y-u-kn", start: 2, end: 15 },
+
+    // Also test when the Unicode extension doesn't start at index 2.
+    { locale: "en-Latn-u-kf", start: 7, end: 12 },
+    { locale: "und-u-kf", start: 3, end: 8 },
+];
+
+for (const {locale, start, end} of testcases) {
+    // Ensure the input is a valid language tag.
+    assertEqArray(Intl.getCanonicalLocales(locale), [locale]);
+
+    assertEq(startOfUnicodeExtensions(locale), start);
+
+    if (start >= 0)
+        assertEq(endOfUnicodeExtensions(locale, start), end);
+}
+
+if (typeof reportCompare === "function")
+    reportCompare(true, true);