json4s problem

json4sproblem.scala

object Test {
  def main(args: Array[String]): Unit = {
    import org.json4s._
    import org.json4s.JsonDSL._
    import org.json4s.native.JsonMethods._
    import org.json4s.native.Serialization
    import org.json4s.native.Serialization.{ read, write, writePretty }
    sealed trait Test
    case object TestA extends Test
    case object TestB extends Test
    case object TestC extends Test

    class TestSerializer extends CustomSerializer[Test](format => (
      {
       case JString("TestA") => TestA
       case JString("TestB") => TestB
       case JString("TestC") => TestC
      },
      {
       case x: Test => JString(x.toString)
      }
    ))

    implicit val jsonFormats =
      Serialization.formats(NoTypeHints) + new TestSerializer

    case class MyCaseClass(test: Test)
    case class MyTest(int: Int, test: Test)

    println(write(TestA)) // Works
    println(write(Map("what" -> TestA))) // Works

    println(write(Map("what" -> MyCaseClass(TestA)))) // Fails with Malformed class name

    println(write(MyCaseClass(TestA))) // Fails with Malformed class name
    println(write(MyCaseClass(TestB))) // Fails with Malformed class name

    println(write(MyTest(10, TestB))) // Fails with Malformed class name
  }
}