testEnterOpensMenu() {
    const node = dom.getElement('demoMenuButton');
    menuButton.decorate(node);
    menuButton.handleKeyEvent(new MyFakeEvent(KeyCodes.ENTER));
    assertTrue('Menu must open after enter', menuButton.isOpen());
  }
Make sure the menu opens when enter is pressed.
@suppress {checkTypes} suppression added to enable type checking