Kotlin ObjectCreationException: Unable to create a random instance of type class

[diego-lima]

I'm trying to use easy-random w/ kotlin 1.7. The scenario I'm about to describe happens with both versions 4.x and 5.x

Consider these statements:

enum class SomeEnum{
    value1,
    value2
}

class Message(
    val code: String,
    val price: Int,
    val someField: SomeEnum
)

class ProductExclusionPolicy : ExclusionPolicy {
    override fun shouldBeExcluded(field: Field, context: RandomizerContext): Boolean {
        return field.name == "price"
    }

    override fun shouldBeExcluded(type: Class<*>?, context: RandomizerContext?): Boolean {
        return false
    }
}

class ProductRandomizerProvider : RandomizerProvider {
    override fun getRandomizerByField(field: Field, context: RandomizerContext): Randomizer<*>? {
        if (field.name == "code") {
            return Randomizer { listOf("213", "377", "465").random() }
        }
    return null
    }
}

These work just fine:

val parameters = EasyRandomParameters()
val easyRandom = EasyRandom(parameters)

val random_message = easyRandom.nextObject(Message::class.java)
println("random_message: ${random_message.code}, ${random_message.price}, ${random_message.someField}")
// random_message: eOMtThyhVNLWUZNRcBaQKxI, -1188957731, value2 

val parameters = EasyRandomParameters()
    .exclusionPolicy(ProductExclusionPolicy())
val easyRandom = EasyRandom(parameters)

val random_message = easyRandom.nextObject(Message::class.java)
println("random_message: ${random_message.code}, ${random_message.price}, ${random_message.someField}")
// random_message: yedUsFwdkelQbxeTeQOvaScfqIOOmaa, 0, value1

If I try to use randomizerProvider, it breaks with ObjectCreationException:

val parameters = EasyRandomParameters()
    .randomizerProvider(ProductRandomizerProvider())
val easyRandom = EasyRandom(parameters)

val random_message = easyRandom.nextObject(Message::class.java)
println("random_message: ${random_message.code}, ${random_message.price}, ${random_message.someField}")
// throws

Stack trace:

Unable to create a random instance of type class Line_2$Message
org.jeasy.random.ObjectCreationException: Unable to create a random instance of type class Line_2$Message
	at org.jeasy.random.EasyRandom.doPopulateBean(EasyRandom.java:172)
	at org.jeasy.random.EasyRandom.nextObject(EasyRandom.java:100)
	at Line_5.<init>(Line_5.jupyter-kts:1)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
	at kotlin.script.experimental.jvm.BasicJvmScriptEvaluator.evalWithConfigAndOtherScriptsResults(BasicJvmScriptEvaluator.kt:105)
	at kotlin.script.experimental.jvm.BasicJvmScriptEvaluator.invoke$suspendImpl(BasicJvmScriptEvaluator.kt:47)
	at kotlin.script.experimental.jvm.BasicJvmScriptEvaluator.invoke(BasicJvmScriptEvaluator.kt)
	at kotlin.script.experimental.jvm.BasicJvmReplEvaluator.eval(BasicJvmReplEvaluator.kt:49)
	at org.jetbrains.kotlinx.jupyter.repl.impl.InternalEvaluatorImpl$eval$resultWithDiagnostics$1.invokeSuspend(InternalEvaluatorImpl.kt:103)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
	at kotlinx.coroutines.EventLoopImplBase.processNextEvent(EventLoop.common.kt:284)
	at kotlinx.coroutines.BlockingCoroutine.joinBlocking(Builders.kt:85)
	at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking(Builders.kt:59)
	at kotlinx.coroutines.BuildersKt.runBlocking(Unknown Source)
	at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking$default(Builders.kt:38)
	at kotlinx.coroutines.BuildersKt.runBlocking$default(Unknown Source)
	at org.jetbrains.kotlinx.jupyter.repl.impl.InternalEvaluatorImpl.eval(InternalEvaluatorImpl.kt:103)
	at org.jetbrains.kotlinx.jupyter.repl.impl.CellExecutorImpl$execute$1$result$1.invoke(CellExecutorImpl.kt:71)
	at org.jetbrains.kotlinx.jupyter.repl.impl.CellExecutorImpl$execute$1$result$1.invoke(CellExecutorImpl.kt:69)
	at org.jetbrains.kotlinx.jupyter.ReplForJupyterImpl.withHost(repl.kt:635)
	at org.jetbrains.kotlinx.jupyter.repl.impl.CellExecutorImpl.execute(CellExecutorImpl.kt:69)
	at org.jetbrains.kotlinx.jupyter.repl.CellExecutor$DefaultImpls.execute$default(CellExecutor.kt:15)
	at org.jetbrains.kotlinx.jupyter.ReplForJupyterImpl$evalEx$1.invoke(repl.kt:444)
	at org.jetbrains.kotlinx.jupyter.ReplForJupyterImpl$evalEx$1.invoke(repl.kt:433)
	at org.jetbrains.kotlinx.jupyter.ReplForJupyterImpl.withEvalContext(repl.kt:397)
	at org.jetbrains.kotlinx.jupyter.ReplForJupyterImpl.evalEx(repl.kt:433)
	at org.jetbrains.kotlinx.jupyter.ReplForJupyterImpl.eval(repl.kt:485)
	at org.jetbrains.kotlinx.jupyter.messaging.ProtocolKt$shellMessagesHandler$2$res$1.invoke(protocol.kt:321)
	at org.jetbrains.kotlinx.jupyter.messaging.ProtocolKt$shellMessagesHandler$2$res$1.invoke(protocol.kt:320)
	at org.jetbrains.kotlinx.jupyter.JupyterExecutorImpl$runExecution$execThread$1.invoke(execution.kt:33)
	at org.jetbrains.kotlinx.jupyter.JupyterExecutorImpl$runExecution$execThread$1.invoke(execution.kt:31)
	at kotlin.concurrent.ThreadsKt$thread$thread$1.run(Thread.kt:30)
Caused by: org.jeasy.random.ObjectCreationException: Unable to create type: int for field: price of class: Line_2$Message
	at org.jeasy.random.FieldPopulator.populateField(FieldPopulator.java:98)
	at org.jeasy.random.EasyRandom.populateField(EasyRandom.java:209)
	at org.jeasy.random.EasyRandom.populateFields(EasyRandom.java:198)
	at org.jeasy.random.EasyRandom.doPopulateBean(EasyRandom.java:165)
	... 35 more
Caused by: org.jeasy.random.ObjectCreationException: Unable to create a random instance of type int
	at org.jeasy.random.EasyRandom.doPopulateBean(EasyRandom.java:172)
	at org.jeasy.random.FieldPopulator.generateRandomValue(FieldPopulator.java:160)
	at org.jeasy.random.FieldPopulator.populateField(FieldPopulator.java:93)
	... 38 more
Caused by: java.lang.IllegalArgumentException: Primitive types can't be instantiated in Java
	at org.objenesis.ObjenesisBase.getInstantiatorOf(ObjenesisBase.java:87)
	at org.objenesis.ObjenesisBase.newInstance(ObjenesisBase.java:73)
	at org.jeasy.random.ObjenesisObjectFactory.createNewInstance(ObjenesisObjectFactory.java:78)
	at org.jeasy.random.ObjenesisObjectFactory.createInstance(ObjenesisObjectFactory.java:65)
	at org.jeasy.random.EasyRandom.doPopulateBean(EasyRandom.java:147)
	... 40 more

but if I add a specific randomizer for all Int fields, it works again:

class ProductRandomizerProvider : RandomizerProvider {
    override fun getRandomizerByField(field: Field, context: RandomizerContext): Randomizer<*>? {
        if (field.name == "code") {
            return Randomizer { listOf("213", "377", "465").random() }
        }
        if (field.type == Int::class.java) {
            return Randomizer { 10 }
        }
    return null
    }
}

val parameters = EasyRandomParameters()
    .randomizerProvider(ProductRandomizerProvider())
val easyRandom = EasyRandom(parameters)
val random_message = easyRandom.nextObject(Message::class.java)
println("random_message: ${random_message.code}, ${random_message.price}, ${random_message.someField}")
// random_message: 465, 10, value2

Why can't I get away with specifying the randomizer for code field only?