public function testGetRootEqualsValueIfSetIfUnpersisted()
 {
     $parent = Category::roots()->first();
     $child = new Category();
     $child->setAttribute($child->getParentColumnName(), $parent->getKey());
     $this->assertEquals($child->getRoot(), $parent);
 }
 public function testChildrenRelationReferesToCorrectField()
 {
     $category = new Category();
     $this->assertEquals($category->getParentColumnName(), $category->children()->getPlainForeignKey());
     $this->assertEquals($category->getQualifiedParentColumnName(), $category->children()->getForeignKey());
 }