ScalaCheck custom list generator and sample property

GenList.scala

package fpinscala.datastructures
import org.scalacheck.{Arbitrary, Gen}

object GenList {
  import fpinscala.datastructures.{Cons, Nil, List}

  def genList[A:Arbitrary]: Gen[List[A]] = for {
    hd <- Arbitrary.arbitrary[A]
    tl <- Gen.oneOf(nilGen, genList[A])
  } yield Cons(hd, tl)

  def nilGen: Gen[List[Nothing]] = Gen.wrap(Nil)

  implicit def arbList[A:Arbitrary] = Arbitrary[List[A]](Gen.oneOf(nilGen, genList[A]))
}

ListSpecification.scala

import org.scalacheck._
import org.scalacheck.Prop.forAll
import fpinscala.datastructures._
import fpinscala.datastructures.GenList._
import fpinscala.datastructures.List._

object ListSpecification extends Properties("List") {

  property("head, setHead and length") = forAll (genList[Int]) { (l) =>
    val h = Arbitrary.arbitrary[Int]
    h == head(setHead(l, h)) && length(l) == length(setHead(l, h))
  }
}