public function testParent()
{
$root = new RootNode();
$parent_one = $this->createParentNode();
$one = $this->createNode();
$parent_one->append($one);
$root->append($parent_one);
$parent_two = $this->createParentNode();
$two = $this->createNode();
$parent_two->append($two);
$root->append($parent_two);
$collection = new NodeCollection([$one, $two]);
$parents = $collection->parent();
$this->assertCount(2, $parents);
$this->assertSame($parent_one, $parents[0]);
$this->assertSame($parent_two, $parents[1]);
$parents = $parents->parent();
$this->assertCount(1, $parents);
$this->assertSame($root, $parents[0]);
$parents = $parents->parent();
$this->assertCount(0, $parents);
}
