public function testGetChildrenOf()
 {
     $entity = new Entity();
     $childrenRelationIndex = $entity->getChildrenRelationIndex();
     $collection = new Collection([$entity, new Entity(), new Entity()]);
     $collection->get(0)->setRelation($childrenRelationIndex, new Collection([new Entity(), new Entity(), new Entity()]));
     $children = $collection->getChildrenOf(0);
     $this->assertInstanceOf('Franzose\\ClosureTable\\Extensions\\Collection', $children);
     $this->assertCount(3, $children);
 }