assert.equal(ShadyDOM.nativeTree.firstElementChild(el), srFirst);
      assert.equal(ShadyDOM.nativeTree.lastElementChild(el), srLast);
      assert.equal(ShadyDOM.nativeTree.parentElement(srFirst), el);
      assert.equal(ShadyDOM.nativeTree.nextElementSibling(srFirst), content);
      assert.equal(ShadyDOM.nativeTree.nextElementSibling(content), srLast);
      assert.equal(ShadyDOM.nativeTree.previousElementSibling(srLast), content);
      assert.equal(ShadyDOM.nativeTree.previousElementSibling(content), 