Set wiki link per user's selected language

src/components/footer/www/footer.jsx

@@ -8,6 +8,7 @@ const FooterBox = require('../container/footer.jsx');
 const LanguageChooser = require('../../languagechooser/languagechooser.jsx');
 
 const frameless = require('../../../lib/frameless');
+const getScratchWikiLink = require('../../../lib/scratch-wiki');
 
 require('./footer.scss');
 
@@ -108,7 +109,7 @@ const Footer = props => (
                         </a>
                     </dd>
                     <dd>
-                        <a href="https://en.scratch-wiki.info/">
+                        <a href={getScratchWikiLink(props.intl.locale)}>
                             <FormattedMessage id="general.wiki" />
                         </a>
                     </dd>

src/lib/scratch-wiki.js

+// This list has to be updated when a new Scratch Wiki is made.
+// Note that wikis under testwiki are not included.
+const wwwLocaleToScratchWikiLocale = {
+    en: 'en',
+    ja: 'ja',
+    fr: 'fr',
+    de: 'de',
+    ru: 'ru',
+    hu: 'hu',
+    nl: 'nl',
+    id: 'id'
+};
+
+const getScratchWikiLink = locale => {
+    if (!wwwLocaleToScratchWikiLocale.hasOwnProperty(locale)) {
+        locale = locale.split('-')[0];
+        if (!wwwLocaleToScratchWikiLocale.hasOwnProperty(locale)) {
+            locale = 'en';
+        }
+    }
+    return `https://${wwwLocaleToScratchWikiLocale[locale]}.scratch-wiki.info/`;
+};
+
+module.exports = getScratchWikiLink;

test/unit/lib/scratch-wiki.test.js

+const getScratchWikiLink = require('../../../src/lib/scratch-wiki');
+
+describe('unit test lib/scratch-wiki.js', () => {
+    test('getScratchWikiLink exists', () => {
+        expect(typeof getScratchWikiLink).toBe('function');
+    });
+
+    test('it returns link to jawiki when ja is given', () => {
+        expect(getScratchWikiLink('ja')).toBe('https://ja.scratch-wiki.info/');
+    });
+
+    test('it returns link to jawiki when ja-Hira is given', () => {
+        expect(getScratchWikiLink('ja-Hira')).toBe('https://ja.scratch-wiki.info/');
+    });
+
+    test('it returns link to enwiki when invalid locale is given', () => {
+        expect(getScratchWikiLink('test')).toBe('https://en.scratch-wiki.info/');
+    });
+});