JSTests/test262/test/intl402/ListFormat/constructor/supportedLocalesOf/basic.js

// Copyright 2018 Google Inc., Igalia S.L. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.

/*---
esid: sec-Intl.ListFormat.supportedLocalesOf
description: >
    Tests that Intl.ListFormat has a supportedLocalesOf property,
    and it works as planned.
features: [Intl.ListFormat]
---*/

assert.sameValue(typeof Intl.ListFormat.supportedLocalesOf, "function",
                 "supportedLocalesOf should be supported.");

const defaultLocale = new Intl.ListFormat().resolvedOptions().locale;
const notSupported = 'zxx'; // "no linguistic content"
const requestedLocales = [defaultLocale, notSupported];

const supportedLocales = Intl.ListFormat.supportedLocalesOf(requestedLocales);
assert.sameValue(supportedLocales.length, 1, 'The length of supported locales list is not 1.');
assert.sameValue(supportedLocales[0], defaultLocale, 'The default locale is not returned in the supported list.');