add test case to demonstrate #218

src/test/scala/com/fasterxml/jackson/module/scala/ser/OverrideValSerializerTest.scala

@@ -0,0 +1,30 @@
+package com.fasterxml.jackson.module.scala.ser
+
+import java.util.UUID
+
+import com.fasterxml.jackson.module.scala.DefaultScalaModule
+import org.junit.runner.RunWith
+import org.scalatestplus.junit.JUnitRunner
+
+@RunWith(classOf[JUnitRunner])
+class OverrideValSerializerTest extends SerializerTest {
+  lazy val module = DefaultScalaModule
+
+  trait MyTrait {
+    val id: UUID
+    val `type`: String
+  }
+
+  class Base(val id: UUID) extends MyTrait {
+    override val `type`: String = "baseclass"
+  }
+
+  case class Sub(override val id: UUID, something: String) extends Base(id)
+
+  "DefaultScalaModule" should "handle overrides in vals" in {
+    val id = UUID.randomUUID()
+    //TODO https://github.com/FasterXML/jackson-module-scala/issues/218
+    //the json should also include "id":"<idAsString>"
+    serialize(Sub(id, "something")) shouldBe """{"type":"baseclass","something":"something"}"""
+  }
+}