DiDom\Element::previousSibling PHP Method

    public function previousSibling()
    {
        if ($this->node->previousSibling === null) {
            return null;
        }
        return new Element($this->node->previousSibling);
    }

 public function testPreviousSibling()
 {
     $html = '<ul><li>One</li><li>Two</li><li>Three</li></ul>';
     $document = new Document($html, false);
     $list = $document->first('ul');
     $item = $list->getNode()->childNodes->item(1);
     $item = new Element($item);
     $previousSibling = $list->getNode()->childNodes->item(0);
     $this->assertEquals($previousSibling, $item->previousSibling()->getNode());
     $item = $list->getNode()->childNodes->item(0);
     $item = new Element($item);
     $this->assertNull($item->previousSibling());
     // with text nodes
     $html = '<p>Foo <span>Bar</span> Baz</p>';
     $document = new Document($html, false);
     $paragraph = $document->first('p');
     $span = $paragraph->first('span');
     $previousSibling = $span->getNode()->previousSibling;
     $this->assertEquals($previousSibling, $span->previousSibling()->getNode());
 }