Toggle the theme on pressing the enter key

src/Header.messages.jsx

@@ -21,6 +21,11 @@ const messages = defineMessages({
     defaultMessage: 'Schools & Partners',
     description: 'Link to the schools and partners landing page',
   },
+  'header.user.theme': {
+    id: 'header.user.theme',
+    defaultMessage: 'Toggle Theme',
+    description: 'Toggle between light and dark theme',
+  },
   'header.user.menu.dashboard': {
     id: 'header.user.menu.dashboard',
     defaultMessage: 'Dashboard',

src/ThemeToggleButton.jsx

@@ -3,11 +3,13 @@ import { getConfig } from '@edx/frontend-platform';
 import Cookies from 'universal-cookie';
 import { Icon } from '@openedx/paragon';
 import { WbSunny, Nightlight } from '@openedx/paragon/icons';
+import { injectIntl, intlShape } from '@edx/frontend-platform/i18n';
+import messages from './Header.messages';
 
 const themeCookie = 'indigo-toggle-dark';
 const themeCookieExpiry = 90; // days
 
-const ThemeToggleButton = () => {
+const ThemeToggleButton = ({ intl }) => {
   const cookies = new Cookies();
   const isThemeToggleEnabled = getConfig().INDIGO_ENABLE_DARK_TOGGLE;
 
@@ -75,6 +77,12 @@ const ThemeToggleButton = () => {
     }
   };
 
+  const hanldeKeyUp = (event) => {
+    if (event.key === 'Enter') {
+      onToggleTheme();
+    }
+  };
+
   if (!isThemeToggleEnabled) {
     return <div />;
   }
@@ -84,7 +92,7 @@ const ThemeToggleButton = () => {
       <div className="light-theme-icon"><Icon src={WbSunny} /></div>
       <div className="toggle-switch">
         <label htmlFor="theme-toggle-checkbox" className="switch">
-          <input id="theme-toggle-checkbox" defaultChecked={cookies.get(themeCookie) === 'dark'} onChange={onToggleTheme} type="checkbox" />
+          <input id="theme-toggle-checkbox" defaultChecked={cookies.get(themeCookie) === 'dark'} onChange={onToggleTheme} onKeyUp={hanldeKeyUp} type="checkbox" title={intl.formatMessage(messages['header.user.theme'])} />
           <span className="slider round" />
         </label>
       </div>
@@ -93,4 +101,9 @@ const ThemeToggleButton = () => {
   );
 };
 
-export default ThemeToggleButton;
+ThemeToggleButton.propTypes = {
+  // i18n
+  intl: intlShape.isRequired,
+};
+
+export default injectIntl(ThemeToggleButton);

src/ThemeToggleButton.test.jsx

@@ -0,0 +1,52 @@
+/* eslint-disable react/prop-types */
+import React from 'react';
+import { IntlProvider } from '@edx/frontend-platform/i18n';
+import { render, fireEvent } from '@testing-library/react';
+import { getConfig } from '@edx/frontend-platform';
+import ThemeToggleButton from './ThemeToggleButton';
+
+jest.mock('@edx/frontend-platform', () => ({
+  getConfig: jest.fn(),
+}));
+
+const mockCookiesGet = jest.fn();
+const mockCookiesSet = jest.fn();
+jest.mock('universal-cookie', () => jest.fn().mockImplementation(() => ({
+  get: mockCookiesGet, // Simulate initial light mode
+  set: mockCookiesSet,
+})));
+
+describe('ThemeToggleButton', () => {
+  beforeEach(() => {
+    getConfig.mockReturnValue({
+      LMS_BASE_URL: 'https://fake.url',
+      INDIGO_ENABLE_DARK_TOGGLE: true,
+    });
+
+    // Reset body class
+    document.body.classList.remove('indigo-dark-theme');
+  });
+
+  it('calls onToggleTheme when Enter key is pressed', () => {
+    mockCookiesGet.mockReturnValue('light');
+
+    const { container } = render(
+      <IntlProvider locale="en" messages={{}}>
+        <ThemeToggleButton />
+      </IntlProvider>,
+    );
+    const checkbox = container.querySelector('#theme-toggle-checkbox');
+    checkbox.focus();
+    fireEvent.keyUp(checkbox, { key: 'Enter' });
+
+    expect(mockCookiesSet).toHaveBeenCalledWith(
+      'indigo-toggle-dark',
+      'dark',
+      expect.objectContaining({
+        domain: 'fake.url',
+        path: '/',
+        expires: expect.any(Date),
+      }),
+    );
+  });
+});