How to test if the case classes I have created for the parser are correct using json4s libraries in scala?

I have a huge json object and I need to parse it and then write some tests to see if everything goes as expected.

case class User(id: Identification, age:Int, name: String ...)
case class Identification(id: Int, hash: String ....)
... a lot more classes

Now I'm trying to write the tests

val json = parse(Source.fromFile(/path).getLines.mkString("\n"))
import org.json4s.DefaultFormats
implicit val formats = DefaultFormats

So my question is how can i test if the case classes are ok? I thought maybe I should try to extract for ex. the users and then to check parameter by parameter if they are correct, but I don't thing that is a good way because it is not me who created the json so I'm not interested about the content.

Thanks