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Can't instantiate proxy for class kotlin.Function2 - similar class definition #997

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Can't instantiate proxy for class kotlin.Function2 - similar class definition#997
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Kotlin bugbug in Kotlin languagebugjava

Description

@rgonciarz
rgonciarz
opened on Dec 10, 2022

JDK 19
Quarkus 2.14.3.Final
Mockk 1.13.3
JUnit 5.9.1

I'm trying to replace an existing instance with mock:

typealias BroadcastSwitchActiveComputer = suspend (Computer) -> Either<BroadcastSwitchActiveComputerError, Unit>

kotlin.jvm.functions.Function2<? super Computer, ? super kotlin.coroutines.Continuation<? super arrow.core.Either<? extends BroadcastSwitchActiveComputerError, ? extends kotlin.Unit>>, ?>

I have several beans with similar Function2 class definition. However they have different Either's generic type.

val typeLiteral = object : TypeLiteral<BroadcastSwitchActiveComputer>() {}
private val mockInstance: BroadcastSwitchActiveComputer = mockk()
val beanInstance = CDI.current().select(typeLiteral, Named("BroadcastSwitchActiveComputer"))
QuarkusMock.installMockForInstance(mockInstance, beanInstance);

A full stack trace:

Failed to create test instance
org.junit.jupiter.api.extension.TestInstantiationException: Failed to create test instance
	at io.quarkus.test.junit.QuarkusTestExtension.initTestState(QuarkusTestExtension.java:773)
	at io.quarkus.test.junit.QuarkusTestExtension.interceptTestClassConstructor(QuarkusTestExtension.java:737)
	at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.lambda$invoke$0(InterceptingExecutableInvoker.java:93)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.api.extension.InvocationInterceptor.interceptTestClassConstructor(InvocationInterceptor.java:73)
	at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.lambda$invoke$0(InterceptingExecutableInvoker.java:93)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.invoke(InterceptingExecutableInvoker.java:92)
	at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.invoke(InterceptingExecutableInvoker.java:62)
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.invokeTestClassConstructor(ClassBasedTestDescriptor.java:363)
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateTestClass(ClassBasedTestDescriptor.java:310)
	at org.junit.jupiter.engine.descriptor.ClassTestDescriptor.instantiateTestClass(ClassTestDescriptor.java:79)
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateAndPostProcessTestInstance(ClassBasedTestDescriptor.java:286)
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$4(ClassBasedTestDescriptor.java:278)
	at java.base/java.util.Optional.orElseGet(Optional.java:364)
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$5(ClassBasedTestDescriptor.java:277)
	at org.junit.jupiter.engine.execution.TestInstancesProvider.getTestInstances(TestInstancesProvider.java:31)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$prepare$0(TestMethodTestDescriptor.java:105)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:104)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:68)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$prepare$2(NodeTestTask.java:123)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.prepare(NodeTestTask.java:123)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:90)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:147)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:127)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:90)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:55)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:102)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.processAllTestClasses(JUnitPlatformTestClassProcessor.java:99)
	at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.access$000(JUnitPlatformTestClassProcessor.java:79)
	at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.stop(JUnitPlatformTestClassProcessor.java:75)
	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:61)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
	at jdk.proxy1/jdk.proxy1.$Proxy2.stop(Unknown Source)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker$3.run(TestWorker.java:193)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:133)
	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:71)
	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
Caused by: java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
	at io.quarkus.runner.bootstrap.RunningQuarkusApplicationImpl.instance(RunningQuarkusApplicationImpl.java:90)
	at io.quarkus.test.junit.QuarkusTestExtension.createActualTestInstance(QuarkusTestExtension.java:779)
	at io.quarkus.test.junit.QuarkusTestExtension.initTestState(QuarkusTestExtension.java:764)
	... 82 more
Caused by: java.lang.reflect.InvocationTargetException
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at io.quarkus.runner.bootstrap.RunningQuarkusApplicationImpl.instance(RunningQuarkusApplicationImpl.java:88)
	... 84 more
Caused by: io.mockk.MockKException: Can't instantiate proxy for class kotlin.Function2
	at io.mockk.impl.instantiation.JvmMockFactory.newProxy(JvmMockFactory.kt:64)
	at io.mockk.impl.instantiation.AbstractMockFactory.newProxy$default(AbstractMockFactory.kt:24)
	at io.mockk.impl.instantiation.AbstractMockFactory.mockk(AbstractMockFactory.kt:59)
	at rg.zerokvm.adapter.api.rest.BroadcastSwitchActiveComputerRestApiAdapterTest.<init>(BroadcastSwitchActiveComputerRestApiAdapterTest.kt:98)
	at rg.zerokvm.adapter.api.rest.BroadcastSwitchActiveComputerRestApiAdapterTest_Bean.create(Unknown Source)
	at rg.zerokvm.adapter.api.rest.BroadcastSwitchActiveComputerRestApiAdapterTest_Bean.get(Unknown Source)
	at rg.zerokvm.adapter.api.rest.BroadcastSwitchActiveComputerRestApiAdapterTest_Bean.get(Unknown Source)
	at io.quarkus.arc.impl.InstanceImpl.getBeanInstance(InstanceImpl.java:226)
	at io.quarkus.arc.impl.InstanceImpl.getInternal(InstanceImpl.java:212)
	at io.quarkus.arc.impl.InstanceImpl.get(InstanceImpl.java:97)
	... 89 more
Caused by: io.mockk.proxy.MockKAgentException: Failed to subclass interface kotlin.jvm.functions.Function2
	at io.mockk.proxy.jvm.ProxyMaker.proxy(ProxyMaker.kt:38)
	at io.mockk.impl.instantiation.JvmMockFactory.newProxy(JvmMockFactory.kt:34)
	... 98 more
Caused by: java.lang.IllegalArgumentException: Could not create type
	at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:170)
	at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:190)
	at io.mockk.proxy.jvm.transformation.SubclassInstrumentation.subclass(SubclassInstrumentation.kt:51)
	at io.mockk.proxy.jvm.ProxyMaker.subclass(ProxyMaker.kt:119)
	at io.mockk.proxy.jvm.ProxyMaker.proxy(ProxyMaker.kt:35)
	... 99 more
Caused by: java.lang.LinkageError: loader 'app' attempted duplicate class definition for kotlin.jvm.functions.Function2$Subclass0. (kotlin.jvm.functions.Function2$Subclass0 is in unnamed module of loader 'app')
	at java.base/java.lang.ClassLoader.defineClass0(Native Method)
	at java.base/java.lang.System$2.defineClass(System.java:2307)
	at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2439)
	at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2416)
	at java.base/java.lang.invoke.MethodHandles$Lookup.defineClass(MethodHandles.java:1843)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at net.bytebuddy.utility.Invoker$Dispatcher.invoke(Unknown Source)
	at net.bytebuddy.utility.dispatcher.JavaDispatcher$Dispatcher$ForNonStaticMethod.invoke(JavaDispatcher.java:1032)
	at net.bytebuddy.utility.dispatcher.JavaDispatcher$ProxiedInvocationHandler.invoke(JavaDispatcher.java:1162)
	at jdk.proxy3/jdk.proxy3.$Proxy102.defineClass(Unknown Source)
	at net.bytebuddy.dynamic.loading.ClassInjector$UsingLookup.injectRaw(ClassInjector.java:1638)
	at net.bytebuddy.dynamic.loading.ClassInjector$AbstractBase.inject(ClassInjector.java:118)
	at net.bytebuddy.dynamic.loading.ClassLoadingStrategy$UsingLookup.load(ClassLoadingStrategy.java:519)
	at net.bytebuddy.dynamic.TypeResolutionStrategy$Passive.initialize(TypeResolutionStrategy.java:101)
	at net.bytebuddy.dynamic.DynamicType$Default$Unloaded.load(DynamicType.java:6317)
	at io.mockk.proxy.jvm.transformation.SubclassInstrumentation.doInterceptedSubclassing(SubclassInstrumentation.kt:98)
	at io.mockk.proxy.jvm.transformation.SubclassInstrumentation.subclass$lambda$0(SubclassInstrumentation.kt:54)
	at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:168)
	... 103 more

Activity

  1. ecjante commented on Feb 3, 2023

    @ecjante
    ecjante
    on Feb 3, 2023

    I am receiving the same Can't instantiate proxy error inconsistently on our CircleCI workflows and has become one of our main "Flaky" test issues.

    This started happening after bumping to version 1.13.4. We have reverted back to 1.13.3 until we can figure out the root cause.

    For our use case, we are simply mocking a kotlin interface for a test.

    private var testDetails: Details? = null
private val billingInventory: IBillingInventory = mockk {
    every { getDetails() } answers { testDetails }
}

    which causes

    io.mockk.MockKException: Can't instantiate proxy for class IBillingInventory
	at app//io.mockk.impl.instantiation.JvmMockFactory.newProxy(JvmMockFactory.kt:64)
	at app//io.mockk.impl.instantiation.AbstractMockFactory.newProxy$default(AbstractMockFactory.kt:24)
	at app//io.mockk.impl.instantiation.AbstractMockFactory.mockk(AbstractMockFactory.kt:59)

    Other instances involve mockking a java class that's provided via Dagger/Hilt which causes the same exception above.

    The main source I can find that could have possibly caused this was this recent change added in 1.13.4 #1025 where ProxyMaker was deduplicated, however, this may have been an issue before hand since the OP experienced this exception in 1.13.3 as well.

    Can anyone shed some light on why the exception is thrown?

  2. ygaller commented on Feb 12, 2023

    @ygaller
    ygaller
    on Feb 12, 2023
    Contributor

    We are seeing something similar. We upgraded from 1.12.2 to 1.13.4. We started seeing flakiness in tests due to the WeakReference. It's likely that there is a GC before the reference is attached to anything.

    package com.test

import io.mockk.proxy.common.CancelableResult
import org.junit.jupiter.api.Test

class MockkTest {

  data class Payload(val something: String)

  @Test
  fun testing() {
    val result = CancelableResult(Payload("hello world"))
    System.gc()
    print(result.get())
  }
}

    Result:

    io.mockk.proxy.MockKAgentException: Value for this result is not assigned

	at io.mockk.proxy.common.CancelableResult.get(CancelableResult.kt:18)
	at com.test.MockkTest.testing(MockkTest.kt:14)
  3. ygaller
    added a commit that references this issue on Feb 15, 2023

    Issue mockk#997 - Simulate garbage collected proxy

    cd2ab2f

  4. ygaller commented on Feb 15, 2023

    @ygaller
    ygaller
    on Feb 15, 2023
    Contributor

    Created a PR with a fix for handling GCs but removing the WeakReference from ProxyMaker: #1052

  5. ygaller
    added 2 commits that reference this issue on Feb 15, 2023

    Issue mockk#997 - Remove weak reference from ProxyMaker due to GC

    e10e401

    Issue mockk#997 - comment

    4ab3ed1
  6. Raibaz
    added a commit that references this issue on Feb 28, 2023

    Merge pull request #1052 from ygaller/issue997

    9a9f072

  7. orafaaraujo commented on Mar 2, 2023

    @orafaaraujo
    orafaaraujo
    on Mar 2, 2023

    Hello

    I came here looking for some answers related to the MockKAgentException: Value for this result is not assigned that we're also facing after updating to version 1.13.4 and found a PR fixing it (many thanks, @ygaller 🙏).

    I noticed that the PR was merged two days ago. Do we have visibility of when the new release will come?

    Thank you in advance

  8. Raibaz commented on Apr 12, 2023

    @Raibaz
    Raibaz
    on Apr 12, 2023
    Collaborator

    Just released 1.13.5!

  9. rschattauer commented on Jun 12, 2023

    @rschattauer
    rschattauer
    on Jun 12, 2023

    I still get Caused by: io.mockk.proxy.MockKAgentException: Value for this result is not assigned on 1.13.5 (not on 1.13.3) when running all tests on random occasions. With jdk17 this problem increased drastically, while with jdk11 it is pretty rare.

  10. mabwah-arista commented on Jul 5, 2023

    @mabwah-arista
    mabwah-arista
    on Jul 5, 2023

    This seems to have undid the fix from #1013, now I still have memory leaks since GC can't collect the spy objects when they're cleared.

  11. Tautellini commented on Sep 21, 2023

    @Tautellini
    Tautellini
    on Sep 21, 2023

    We also have increased flakyness in our tests after updating to JDK17 and Mockk Android 1.13.4.
    We also downgraded for now.

    We got the following issues very frequently:
    MockKException: Can't instantiate proxy for class
    java.lang.InstantiationError
    MockKAgentException: Value for this result is not assigned

    Would like to add, that the only other change we have done is using the JVM parallel garbage collector as mentioned in an Android Documentation:
    https://developer.android.com/build/optimize-your-build#experiment-with-the-jvm-parallel-garbage-collector

    We also disabled that for now.

    Can this be related?

  12. JooHyukKim commented on Nov 28, 2023

    @JooHyukKim
    JooHyukKim
    on Nov 28, 2023

    We are seeing something similar. We upgraded from 1.12.2 to 1.13.4. We started seeing flakiness in tests due to the WeakReference. It's likely that there is a GC before the reference is attached to anything.

    May I ask if this

    io.mockk.proxy.MockKAgentException: Value for this result is not assigned

    ... issue fixed in 1.13.5, @ygaller? I am experiencing same issue.

  13. ygaller commented on Nov 29, 2023

    @ygaller
    ygaller
    on Nov 29, 2023
    Contributor

    @JooHyukKim Yes this is fixed in 1.13.5

  14. JooHyukKim commented on Nov 29, 2023

    @JooHyukKim
    JooHyukKim
    on Nov 29, 2023

    @ygaller Thank you for letting me know! 👍🏼

  15. github-actions
    added
    bug
    java
    Kotlin bugbug in Kotlin language
    on Aug 14, 2025
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