integration-test: Start writing test for language change

integration-tests/i18n.spec.ts

@@ -0,0 +1,20 @@
+import test, { expect } from "@playwright/test";
+
+test("User can change language from settings", async ({ page }) => {
+    // Clear all tabs
+    await page.locator('.note-tab:first-of-type').locator("div").nth(1).click({ button: 'right' });
+    await page.getByText('Close all tabs').click();
+
+    // Go to options
+    await page.locator('#launcher-pane div').filter({ hasText: 'Options Open New Window' }).getByRole('button').click();
+    await page.locator('#launcher-pane').getByText('Options').click();
+
+    // Check that the default value (English) is set.
+    await expect(page.locator('#center-pane')).toContainText('Theme');    
+    const languageCombobox = await page.getByRole('combobox').first();
+    expect(languageCombobox).toHaveValue("en");
+
+    // Select Chinese and ensure the translation is set.
+    languageCombobox.selectOption("cn");
+    await expect(page.locator('#center-pane')).toContainText('主题');
+});