test('disabled checkbox cannot be clicked', function(done) {
        c1.disabled = true;
        c1.checked = true;
        MockInteractions.tap(c1);
        setTimeout(function() {
          assert.isTrue(c1.getAttribute('aria-checked') == 'true');
          assert.isTrue(c1.checked);
          done();
        }, 1);
      });

      test('checkbox can be validated', function() {
        c1.required = true;
        assert.isFalse(c1.validate());

        c1.checked = true;
        assert.isTrue(c1.validate