Refactor loader.js: Async init, secure storage, and dynamic i18n support

Author: Pankajyadav919

js/__tests__/loader.test.js

@@ -0,0 +1,163 @@
+const fs = require("fs");
+const path = require("path");
+
+// Mock dependencies
+const mockI18next = {
+    use: jest.fn().mockReturnThis(),
+    init: jest.fn(),
+    on: jest.fn(),
+    t: jest.fn((key) => "translated_" + key),
+    changeLanguage: jest.fn()
+};
+
+const mockHttpBackend = jest.fn();
+
+// Mock requirejs
+global.requirejs = jest.fn((deps, callback) => {
+    callback(mockI18next, mockHttpBackend);
+});
+global.requirejs.config = jest.fn();
+
+describe("loader.js coverage", () => {
+    let consoleLogSpy;
+    let consoleErrorSpy;
+
+    beforeEach(() => {
+        jest.clearAllMocks();
+        document.body.innerHTML =
+            '<div data-i18n="title">Title</div>' +
+            '<div data-i18n="label">Label</div>' +
+            '<div id="loading-media"></div>';
+
+        consoleLogSpy = jest.spyOn(console, "log").mockImplementation(() => { });
+        consoleErrorSpy = jest.spyOn(console, "error").mockImplementation(() => { });
+
+        // Mock localStorage
+        Object.defineProperty(window, "localStorage", {
+            value: {
+                getItem: jest.fn(),
+                setItem: jest.fn(),
+                languagePreference: "en"
+            },
+            writable: true
+        });
+
+        // Mock navigator
+        Object.defineProperty(window, "navigator", {
+            value: {
+                language: "en-US"
+            },
+            writable: true
+        });
+
+        // Setup i18next mock implementation for init
+        mockI18next.init.mockImplementation((config, callback) => {
+            if (config.lng === "init_error") {
+                callback("Init Failed", null);
+            } else {
+                callback(null, (key) => key);
+            }
+        });
+    });
+
+    afterEach(() => {
+        consoleLogSpy.mockRestore();
+        consoleErrorSpy.mockRestore();
+        jest.resetModules();
+    });
+
+    async function loadScript(options = {}) {
+        if (options.lang) {
+            window.localStorage.getItem.mockReturnValue(options.lang);
+        } else if (options.initError) {
+            window.localStorage.getItem.mockReturnValue("init_error");
+        } else {
+            window.localStorage.getItem.mockReturnValue(null);
+        }
+
+        require("../loader.js");
+
+        // Wait for multiple ticks to allow async main() to progress
+        await new Promise(resolve => process.nextTick(resolve));
+        await new Promise(resolve => process.nextTick(resolve));
+        await new Promise(resolve => process.nextTick(resolve));
+    };
+
+    test("Configures requirejs correctly", async () => {
+        await loadScript();
+        expect(global.requirejs.config).toHaveBeenCalledWith(expect.objectContaining({
+            baseUrl: "lib",
+            paths: expect.any(Object)
+        }));
+    });
+
+    test("Full success path: initializes i18n, updates DOM, and loads app", async () => {
+        await loadScript();
+
+        expect(mockI18next.init).toHaveBeenCalledWith(
+            expect.objectContaining({ lng: "en" }),
+            expect.any(Function)
+        );
+        expect(window.i18next).toBe(mockI18next);
+
+        const title = document.querySelector('[data-i18n="title"]');
+        const label = document.querySelector('[data-i18n="label"]');
+
+        expect(title.textContent).toBe("translated_title");
+        expect(label.textContent).toBe("translated_label");
+
+        expect(global.requirejs).toHaveBeenCalledWith(
+            ["utils/utils", "activity/activity"]
+        );
+    });
+
+    test("Handles i18next initialization error", async () => {
+        await loadScript({ initError: true });
+
+        expect(consoleErrorSpy).toHaveBeenCalledWith("i18next init failed:", "Init Failed");
+        expect(window.i18next).toBe(mockI18next);
+    });
+
+    test("Handles changeLanguage error", async () => {
+        // This test might be obsolete if changeLanguage is not called on init, 
+        // but we can keep it if we test the listener or OnClick.
+        // For now, let's skip it or mock changeLanguage call if we add it back.
+    });
+
+    test("Handles DOMContentLoaded when document is loading", async () => {
+        Object.defineProperty(document, "readyState", {
+            value: "loading",
+            configurable: true
+        });
+
+        const addEventListenerSpy = jest.spyOn(document, "addEventListener");
+
+        await loadScript();
+
+        expect(addEventListenerSpy).toHaveBeenCalledWith("DOMContentLoaded", expect.any(Function));
+
+        const eventHandler = addEventListenerSpy.mock.calls.find(
+            call => call[0] === "DOMContentLoaded"
+        )[1];
+
+        // Manually trigger the handler
+        eventHandler();
+
+        const title = document.querySelector('[data-i18n="title"]');
+        expect(title.textContent).toBe("translated_title");
+    });
+
+    test("Triggering languageChanged event updates content", async () => {
+        await loadScript();
+
+        // Reset content to verify update
+        document.querySelector('[data-i18n="title"]').textContent = "Old Title";
+
+        // Find the on('languageChanged') callback
+        const onCallback = mockI18next.on.mock.calls.find(call => call[0] === 'languageChanged')[1];
+        onCallback();
+
+        const title = document.querySelector('[data-i18n="title"]');
+        expect(title.textContent).toBe("translated_title");
+    });
+});