IRunnable.kt

interface IRunnable {
  fun run()
}

class Horse : IRunnable {
  override fun run() {
    println("horse running")
  }
}

class Dog : IRunnable {
  override fun run() {
    println("dog running")
  }
}

RunnableTest.kt

class RunnableTest {

  private val logger = KotlinLogging.logger { }

  @Serializer(forClass = Horse::class)
  object HorseSerializer {}

  @Serializer(forClass = Dog::class)
  object DogSerializer {}

  @ImplicitReflectionSerializer
  @Test
  fun testJson() {

    val runnableModule = SerializersModule {
      polymorphic(IRunnable::class) {
        Horse::class with HorseSerializer
        Dog::class with DogSerializer
      }
    }

    Json(context = runnableModule).stringify(Horse::class.serializer(), Horse()).also {
      logger.info("json = {}", it)
    }
  }
}


/**
kotlinx.serialization.SerializationException: Can't locate argument-less serializer for class Horse. For generic classes, such as lists, please provide serializer explicitly.

	at kotlinx.serialization.PlatformUtilsKt.serializer(PlatformUtils.kt:12)
	at RunnableTest.testJson(RunnableTest.kt:30)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
  **/

RunnableTest2.kt

class RunnableTest2 {

  private val logger = KotlinLogging.logger { }

  @Serializer(forClass = Horse::class)
  object HorseSerializer {}

  @Serializer(forClass = Dog::class)
  object DogSerializer {}

  @ImplicitReflectionSerializer
  @Test
  fun testJson() {

    val runnableModule = SerializersModule {
      polymorphic(IRunnable::class) {
        Horse::class with HorseSerializer
        Dog::class with DogSerializer
      }
    }

    Json(context = runnableModule).stringify(IRunnable::class.serializer(), Horse()).also {
      logger.info("json = {}", it)
    }
  }
}

/**

kotlinx.serialization.SerializationException: Can't locate argument-less serializer for class IRunnable. For generic classes, such as lists, please provide serializer explicitly.

	at kotlinx.serialization.PlatformUtilsKt.serializer(PlatformUtils.kt:12)
	at RunnableTest.testJson(RunnableTest.kt:30)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
  */