add tests

src/utils/__tests__/l10n.js

@@ -0,0 +1,17 @@
+import * as utils from '../l10n';
+
+describe('l10n utils: getInitialLocale', () => {
+    it('default lang', () => {
+        expect(utils.getInitialLocale(0)).toBe('en');
+        expect(utils.getInitialLocale(null)).toBe('en');
+        expect(utils.getInitialLocale(undefined)).toBe('en');
+        expect(utils.getInitialLocale('dadada')).toBe('en');
+        expect(utils.getInitialLocale('')).toBe('en');
+    });
+
+    it('browser locales', () => {
+        expect(utils.getInitialLocale('zh')).toBe('zh');
+        expect(utils.getInitialLocale('cs-CZ')).toBe('cs');
+        expect(utils.getInitialLocale('en_GB')).toBe('en');
+    });
+});