public function testSiblings()
 {
     $root = new RootNode();
     $parent_one = $this->createParentNode();
     $parent_one->appendTo($root);
     $one = $this->createNode();
     $one->appendTo($parent_one);
     $two = $this->createNode();
     $two->appendTo($parent_one);
     $three = $this->createNode();
     $three->appendTo($parent_one);
     $parent_two = $this->createParentNode();
     $parent_two->appendTo($root);
     $first = $this->createNode();
     $first->appendTo($parent_two);
     $second = $this->createNode();
     $second->appendTo($parent_two);
     $third = $this->createNode();
     $third->appendTo($parent_two);
     $collection = new NodeCollection([$two, $second], FALSE);
     $matches = $collection->siblings();
     $this->assertCount(4, $matches);
     $this->assertSame($one, $matches[0]);
     $this->assertSame($three, $matches[1]);
     $this->assertSame($first, $matches[2]);
     $this->assertSame($third, $matches[3]);
 }