[test] add test for i18n currentLocale

test/frontend.spec.js

@@ -0,0 +1,42 @@
+// eslint-disable-next-line no-global-assign
+global.localStorage = {};
+global.navigator = {
+    language: "en"
+};
+
+const { currentLocale } = require("../src/i18n");
+
+describe("Test i18n.js", () => {
+
+    it("currentLocale()", () => {
+        expect(currentLocale()).toEqual("en");
+
+        navigator.language = "zh-HK";
+        expect(currentLocale()).toEqual("zh-HK");
+
+        // Note that in Safari on iOS prior to 10.2, the country code returned is lowercase: "en-us", "fr-fr" etc.
+        // https://developer.mozilla.org/en-US/docs/Web/API/Navigator/language
+        navigator.language = "zh-hk";
+        expect(currentLocale()).toEqual("en");
+
+        navigator.language = "en-US";
+        expect(currentLocale()).toEqual("en");
+
+        navigator.language = "ja-ZZ";
+        expect(currentLocale()).toEqual("ja");
+
+        navigator.language = "zz";
+        expect(currentLocale()).toEqual("en");
+
+        navigator.language = "zz-ZZ";
+        expect(currentLocale()).toEqual("en");
+
+        localStorage.locale = "en";
+        expect(currentLocale()).toEqual("en");
+
+        localStorage.locale = "zh-HK";
+        expect(currentLocale()).toEqual("zh-HK");
+    });
+
+});
+