testCheckboxReceiveEvents() {
    const node = dom.getElement('demoSelectionMenuButton');
    selectionMenuButton.decorate(node);

    const checkbox = dom.getElement('demoCheckbox');
    assertFalse(
        'Checkbox must be unchecked (i.e. unselected)', checkbox.checked);

    testingEvents.fireClickSequence(dom.getElement('menuItem1'));
    assertTrue('Checkbox must be checked (i.e. selected)', checkbox.checked);

    testingEvents.fireClickSequence(dom.getElement('menuItem2'));
    assertFalse(
        'Checkbox must be unchecked (i.e. unselected)', checkbox.checked);
  }
Tests that the checkbox state gets updated when the first 2 events fire
     @suppress {strictMissingProperties} suppression added to enable type
     checking