      
      test('get items', function() {
        assert.equal(s.$.selector.items.length, s.children.length);
      });
      
      test('activate event', function(done) {
        s.children[2].dispatchEvent(new CustomEvent('tap', {bubbles: true}));
        asyncPlatformFlush(function() {
          // check selected class
          assert.isTrue(s.children[2].classList.contains('core-selected'));
          done();
        });
      });
      
      test('add item dynamically', function(done) {
        va