Value class unboxing fails when mocked function and caller have the same name

[fthouraud]

Hi 👋

I stumbled upon a strange behavior after upgrading my project to Mockk 1.13.10.

It involves context receiver and I understand that you don't officially support this feature but I think it could be reported for future support.

Expected behavior

When I mock an extension function returning a Result, I expect it to return the Result as requested whatever the caller context is.

It works as expected with Mockk 1.13.9.

Current behavior

When the calling function has a context receiver and has the same name as the mocked extension function, it fails at trying to unbox the value of the Result.

Failure context

Kotlin : 1.9.22
Mockk : 1.13.10
JDK : 17 & 21

Step to reproduce

1. Write a function having a context receiver and returning a Result
2. Write an extension function with the same name as the previous one and also returning a Result
3. Call the extension function from the top-level function
4. Write a test that only mocks the extension function
5. The test should fail with a similar stacktrace as the reported one.

Stacktrace

kotlin.reflect.jvm.internal.KotlinReflectionInternalError: Inconsistent number of parameters in the descriptor and Java reflection object: 3 != 2
Calling: context(me.fth.sandbox.FakeContext) public fun createFoo(foo: me.fth.sandbox.Foo, bar: me.fth.sandbox.Bar): kotlin.Result<me.fth.sandbox.Foo> defined in me.fth.sandbox[DeserializedSimpleFunctionDescriptor@53d9826f]
Parameter types: [interface me.fth.sandbox.FakeContext, class me.fth.sandbox.Foo, class me.fth.sandbox.Bar])
Default: false
	at kotlin.reflect.jvm.internal.calls.ValueClassAwareCallerKt.checkParametersSize(ValueClassAwareCaller.kt:251)
	at kotlin.reflect.jvm.internal.calls.ValueClassAwareCallerKt.access$checkParametersSize(ValueClassAwareCaller.kt:1)
	at kotlin.reflect.jvm.internal.calls.ValueClassAwareCaller.<init>(ValueClassAwareCaller.kt:105)
	at kotlin.reflect.jvm.internal.calls.ValueClassAwareCallerKt.createValueClassAwareCallerIfNeeded(ValueClassAwareCaller.kt:292)
	at kotlin.reflect.jvm.internal.calls.ValueClassAwareCallerKt.createValueClassAwareCallerIfNeeded$default(ValueClassAwareCaller.kt:281)
	at kotlin.reflect.jvm.internal.KFunctionImpl$caller$2.invoke(KFunctionImpl.kt:99)
	at kotlin.reflect.jvm.internal.KFunctionImpl$caller$2.invoke(KFunctionImpl.kt:64)
	at kotlin.SafePublicationLazyImpl.getValue(LazyJVM.kt:107)
	at kotlin.reflect.jvm.internal.KFunctionImpl.getCaller(KFunctionImpl.kt:64)
	at kotlin.reflect.jvm.ReflectJvmMapping.getJavaMethod(ReflectJvmMapping.kt:64)
	at kotlin.reflect.jvm.ReflectJvmMapping.findKFunction(ReflectJvmMapping.kt:152)
	at kotlin.reflect.jvm.ReflectJvmMapping.getKotlinFunction(ReflectJvmMapping.kt:131)
	at io.mockk.core.ValueClassSupport.maybeUnboxValueForMethodReturn(ValueClassSupport.kt:26)
	at io.mockk.proxy.jvm.advice.Interceptor.call(Interceptor.kt:22)
	at me.fth.sandbox.FooServiceKt.createFoo(FooService.kt:12)
	at me.fth.sandbox.FooServiceKt.createFoo(FooService.kt:10)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at io.mockk.proxy.jvm.advice.MethodCall.call(MethodCall.kt:14)
	at io.mockk.proxy.jvm.advice.SelfCallEliminatorCallable.call(SelfCallEliminatorCallable.kt:14)
	at io.mockk.impl.instantiation.JvmMockFactoryHelper.handleOriginalCall(JvmMockFactoryHelper.kt:96)
	at io.mockk.impl.instantiation.JvmMockFactoryHelper.access$handleOriginalCall(JvmMockFactoryHelper.kt:19)
	at io.mockk.impl.instantiation.JvmMockFactoryHelper$mockHandler$1$invocation$1$1.invoke(JvmMockFactoryHelper.kt:28)
	at io.mockk.impl.stub.MockKStub$handleInvocation$originalPlusToString$1.invoke(MockKStub.kt:233)
	at io.mockk.impl.stub.SpyKStub.defaultAnswer(SpyKStub.kt:15)
	at io.mockk.impl.stub.MockKStub.answer(MockKStub.kt:42)
	at io.mockk.impl.recording.states.AnsweringState.call(AnsweringState.kt:16)
	at io.mockk.impl.recording.CommonCallRecorder.call(CommonCallRecorder.kt:53)
	at io.mockk.impl.stub.MockKStub.handleInvocation(MockKStub.kt:269)
	at io.mockk.impl.instantiation.JvmMockFactoryHelper$mockHandler$1.invocation(JvmMockFactoryHelper.kt:24)
	at io.mockk.proxy.jvm.advice.Interceptor.call(Interceptor.kt:21)
	at me.fth.sandbox.FooServiceKt.createFoo(FooService.kt:10)
	at me.fth.sandbox.FooServiceTest.will fail when mocking extension function having the same name has the caller with a context(FooServiceTest.kt:19)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$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.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$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$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$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$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.processAllTestClasses(JUnitPlatformTestClassProcessor.java:110)
	at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.access$000(JUnitPlatformTestClassProcessor.java:90)
	at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.stop(JUnitPlatformTestClassProcessor.java:85)
	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:62)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
	at org.gradle.internal.dispatch.ProxyDispatchAdapter$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:113)
	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)

Minimal reproducible code (the gist of this issue)

/* GRADLE */
plugins {
    kotlin("jvm") version "1.9.22"
}

dependencies {
    testImplementation("io.mockk:mockk:1.13.10")
    testImplementation(kotlin("test"))
}

tasks.test {
    useJUnitPlatform()
}

tasks.withType<KotlinCompile> {
    kotlinOptions.freeCompilerArgs += "-Xcontext-receivers"
}

/* TESTED CODE */
package me.fth.sandbox

data class Foo(val title: String)

data class Bar(val value: Int)

interface FakeContext

context(FakeContext)
fun createFoo(foo: Foo, bar: Bar): Result<Foo> = bar.createFoo(foo)

fun Bar.createFoo(foo: Foo) = Result.success(foo)

context(FakeContext)
fun createNewFoo(foo: Foo, bar: Bar): Result<Foo> = bar.newFoo(foo)

fun Bar.newFoo(foo: Foo) = Result.success(foo)

/* TEST */
package me.fth.sandbox

import io.mockk.every
import io.mockk.mockkStatic
import kotlin.test.Test
import kotlin.test.assertEquals

class FooServiceTest {
    val foo = Foo("It should not fail.")
    val bar = Bar(42)

    @Test
    fun `it will fail when mocking extension function having the same name has the caller with a context`() {
        mockkStatic(Bar::createFoo)

        every { bar.createFoo(foo) } returns Result.success(foo)

        with(object : FakeContext {}) {
            assertEquals(foo, createFoo(foo, bar).getOrThrow())
        }
    }

    @Test
    fun `it will succeed when the extension function does not have the same name as the caller with a context`() {
        mockkStatic(Bar::newFoo)

        every { bar.newFoo(foo) } returns Result.success(foo)

        with(object : FakeContext {}) {
            assertEquals(foo, createNewFoo(foo, bar).getOrThrow())
        }
    }
}

Workaround

As a workaround, simply rename either the top-level function or the extension function.

I hope it could be of some help.

[fthouraud]

I'd like to add that my IDE sees the top-level function as an overloading of the extension function. So it could be related to Kotlin but only revealed by the recent changes on Mockk.