public function itSetsTheParentNodeOfTheChildren()
{
$root = new TreeNode();
$node_1 = new TreeNode();
$node_2 = new TreeNode();
$children = array($node_1, $node_2);
$root->setChildren($children);
$this->assertEqual($root, $node_2->getParentNode());
$this->assertEqual($root, $node_1->getParentNode());
}
private function getParentNodeId(TreeNode $node)
{
$parent_node = $node->getParentNode();
return $parent_node ? $parent_node->getId() : 0;
}