Cannot create mock of interface, but of implementing class (method type parameters involved)

[milgner]

Expected Behavior

Given the following interface:

interface QueryFacade {
    /**
     * @see [Statistics]
     */
    fun <AT, AF> statistics(
        dataResource: DataResource,
        queryOptions: DataPointQueryOptions,
        aggregateFunctions: NonEmptySet<AF>
    ): AggregatedValues<AF, AT> where AF : AggregateFunction<AT>, AF : Enum<AF>
}

I' d like to create a mock of it by calling mockk<QueryFacade>() and set up responses via every.

Current Behavior

Something about the type parameters seems to confuse the library, or rather bytebuddy and produces the message

Can't instantiate proxy for class io.redigital.core.data.hub.query.QueryFacade

Strangely enough, if I take a class that implements the interface and create a mock of it via mockk<QueryFacadeImpl>(), it works as expected.

Context

Please provide any relevant information about your setup. This is important in case the issue is not reproducible except for under certain conditions.

• MockK version: 1.13.9
• OS: Linux 64 bit
• Kotlin version: 1.9.21
• JDK version: OpenJDK 17
• JUnit version: 5.10.1
• Type of test: unit test

Stack trace

io.mockk.MockKException: Can't instantiate proxy for class io.redigital.core.data.hub.query.QueryFacade
	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 io.redigital.core.data.hub.graphql.StatisticsQuerySpec$1$1.invokeSuspend(StatisticsQuerySpec.kt:47)
	at io.redigital.core.data.hub.graphql.StatisticsQuerySpec$1$1.invoke(StatisticsQuerySpec.kt)
	at io.redigital.core.data.hub.graphql.StatisticsQuerySpec$1$1.invoke(StatisticsQuerySpec.kt)
	at io.kotest.core.spec.style.scopes.RootScopeKt$addTest$1.invokeSuspend(RootScope.kt:36)
	at io.kotest.core.spec.style.scopes.RootScopeKt$addTest$1.invoke(RootScope.kt)
	at io.kotest.core.spec.style.scopes.RootScopeKt$addTest$1.invoke(RootScope.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$innerExecute$1.invokeSuspend(TestCaseExecutor.kt:91)
	at io.kotest.engine.test.TestCaseExecutor$execute$innerExecute$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$innerExecute$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.CoroutineDebugProbeInterceptor.intercept(CoroutineDebugProbeInterceptor.kt:29)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestInvocationInterceptor$runBeforeTestAfter$executeWithBeforeAfter$1.invokeSuspend(TestInvocationInterceptor.kt:63)
	at io.kotest.engine.test.TestInvocationInterceptor$runBeforeTestAfter$executeWithBeforeAfter$1.invoke(TestInvocationInterceptor.kt)
	at io.kotest.engine.test.TestInvocationInterceptor$runBeforeTestAfter$executeWithBeforeAfter$1.invoke(TestInvocationInterceptor.kt)
	at io.kotest.engine.test.interceptors.InvocationTimeoutInterceptor$intercept$3.invokeSuspend(InvocationTimeoutInterceptor.kt:43)
	at io.kotest.engine.test.interceptors.InvocationTimeoutInterceptor$intercept$3.invoke(InvocationTimeoutInterceptor.kt)
	at io.kotest.engine.test.interceptors.InvocationTimeoutInterceptor$intercept$3.invoke(InvocationTimeoutInterceptor.kt)
	at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturnIgnoreTimeout(Undispatched.kt:89)
	at kotlinx.coroutines.TimeoutKt.setupTimeout(Timeout.kt:151)
	at kotlinx.coroutines.TimeoutKt.withTimeoutOrNull(Timeout.kt:107)
	at io.kotest.engine.test.interceptors.InvocationTimeoutInterceptor.intercept(InvocationTimeoutInterceptor.kt:42)
	at io.kotest.engine.test.TestInvocationInterceptor$runBeforeTestAfter$wrappedTest$1$1.invokeSuspend(TestInvocationInterceptor.kt:70)
	at io.kotest.engine.test.TestInvocationInterceptor$runBeforeTestAfter$wrappedTest$1$1.invoke(TestInvocationInterceptor.kt)
	at io.kotest.engine.test.TestInvocationInterceptor$runBeforeTestAfter$wrappedTest$1$1.invoke(TestInvocationInterceptor.kt)
	at io.kotest.engine.test.TestInvocationInterceptor.runBeforeTestAfter(TestInvocationInterceptor.kt:73)
	at io.kotest.engine.test.TestInvocationInterceptor.access$runBeforeTestAfter(TestInvocationInterceptor.kt:14)
	at io.kotest.engine.test.TestInvocationInterceptor$intercept$2$1.invokeSuspend(TestInvocationInterceptor.kt:36)
	at io.kotest.engine.test.TestInvocationInterceptor$intercept$2$1.invoke(TestInvocationInterceptor.kt)
	at io.kotest.engine.test.TestInvocationInterceptor$intercept$2$1.invoke(TestInvocationInterceptor.kt)
	at io.kotest.mpp.ReplayKt.replay(replay.kt:15)
	at io.kotest.engine.test.TestInvocationInterceptor$intercept$2.invokeSuspend(TestInvocationInterceptor.kt:32)
	at io.kotest.engine.test.TestInvocationInterceptor$intercept$2.invoke(TestInvocationInterceptor.kt)
	at io.kotest.engine.test.TestInvocationInterceptor$intercept$2.invoke(TestInvocationInterceptor.kt)
	at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undispatched.kt:78)
	at kotlinx.coroutines.CoroutineScopeKt.coroutineScope(CoroutineScope.kt:264)
	at io.kotest.engine.test.TestInvocationInterceptor.intercept(TestInvocationInterceptor.kt:31)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.interceptors.MarkAbortedExceptionsAsSkippedTestInterceptor.intercept(MarkAbortedExceptionsAsSkippedTestInterceptor.kt:23)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.ExpectExceptionTestInterceptor.intercept(ExpectExceptionTestInterceptor.kt:18)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.TimeoutInterceptor.intercept(TimeoutInterceptor.kt:33)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.BlockedThreadTimeoutInterceptor.intercept(BlockedThreadTimeoutInterceptor.kt:79)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.CoroutineLoggingInterceptor.intercept(CoroutineLoggingInterceptor.kt:30)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.SoftAssertInterceptor.intercept(SoftAssertInterceptor.kt:27)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.AssertionModeInterceptor.intercept(AssertionModeInterceptor.kt:25)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.LifecycleInterceptor.intercept(LifecycleInterceptor.kt:50)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor$intercept$2.invokeSuspend(TestCaseExtensionInterceptor.kt:24)
	at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor$intercept$2.invoke(TestCaseExtensionInterceptor.kt)
	at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor$intercept$2.invoke(TestCaseExtensionInterceptor.kt)
	at io.kotest.engine.test.TestExtensions.intercept(TestExtensions.kt:148)
	at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor.intercept(TestCaseExtensionInterceptor.kt:24)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.BeforeSpecListenerInterceptor.intercept(BeforeSpecListenerInterceptor.kt:43)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.TestEnabledCheckInterceptor.intercept(TestEnabledCheckInterceptor.kt:31)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor$intercept$3.invokeSuspend(CoroutineErrorCollectorInterceptor.kt:34)
	at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor$intercept$3.invoke(CoroutineErrorCollectorInterceptor.kt)
	at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor$intercept$3.invoke(CoroutineErrorCollectorInterceptor.kt)
	at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undispatched.kt:78)
	at kotlinx.coroutines.BuildersKt__Builders_commonKt.withContext(Builders.common.kt:167)
	at kotlinx.coroutines.BuildersKt.withContext(Unknown Source)
	at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor.intercept(CoroutineErrorCollectorInterceptor.kt:33)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
	at io.kotest.engine.test.interceptors.CoroutineDispatcherFactoryInterceptor$intercept$4.invokeSuspend(coroutineDispatcherFactoryInterceptor.kt:57)
	at io.kotest.engine.test.interceptors.CoroutineDispatcherFactoryInterceptor$intercept$4.invoke(coroutineDispatcherFactoryInterceptor.kt)
	at io.kotest.engine.test.interceptors.CoroutineDispatcherFactoryInterceptor$intercept$4.invoke(coroutineDispatcherFactoryInterceptor.kt)
	at io.kotest.engine.concurrency.FixedThreadCoroutineDispatcherFactory$withDispatcher$4.invokeSuspend(FixedThreadCoroutineDispatcherFactory.kt:59)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:108)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: io.mockk.proxy.MockKAgentException: Failed to subclass interface io.redigital.core.data.hub.query.QueryFacade
	at io.mockk.proxy.jvm.ProxyMaker.proxy(ProxyMaker.kt:42)
	at io.mockk.impl.instantiation.JvmMockFactory.newProxy(JvmMockFactory.kt:34)
	... 110 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:50)
	at io.mockk.proxy.jvm.ProxyMaker.subclass(ProxyMaker.kt:130)
	at io.mockk.proxy.jvm.ProxyMaker.proxy(ProxyMaker.kt:39)
	... 111 more
Caused by: java.lang.IllegalArgumentException: Unknown type: null
	at net.bytebuddy.description.type.TypeDefinition$Sort.describe(TypeDefinition.java:280)
	at net.bytebuddy.description.type.TypeDescription$Generic$OfWildcardType$ForLoadedType$WildcardUpperBoundTypeList.get(TypeDescription.java:4836)
	at net.bytebuddy.description.type.TypeDescription$Generic$OfWildcardType$ForLoadedType$WildcardUpperBoundTypeList.get(TypeDescription.java:4809)
	at net.bytebuddy.matcher.FilterableList$AbstractBase.getOnly(FilterableList.java:141)
	at net.bytebuddy.description.type.TypeDescription$Generic$Visitor$ForSignatureVisitor$OfTypeArgument.onWildcard(TypeDescription.java:1851)
	at net.bytebuddy.description.type.TypeDescription$Generic$Visitor$ForSignatureVisitor$OfTypeArgument.onWildcard(TypeDescription.java:1835)
	at net.bytebuddy.description.type.TypeDescription$Generic$OfWildcardType.accept(TypeDescription.java:4691)
	at net.bytebuddy.description.type.TypeDescription$Generic$Visitor$ForSignatureVisitor.onOwnableType(TypeDescription.java:1804)
	at net.bytebuddy.description.type.TypeDescription$Generic$Visitor$ForSignatureVisitor.onParameterizedType(TypeDescription.java:1785)
	at net.bytebuddy.description.type.TypeDescription$Generic$Visitor$ForSignatureVisitor.onParameterizedType(TypeDescription.java:1743)
	at net.bytebuddy.description.type.TypeDescription$Generic$OfParameterizedType.accept(TypeDescription.java:5134)
	at net.bytebuddy.description.method.MethodDescription$AbstractBase.getGenericSignature(MethodDescription.java:552)
	at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod.apply(TypeWriter.java:612)
	at net.bytebuddy.dynamic.scaffold.TypeWriter$Default$ForCreation.create(TypeWriter.java:6043)
	at net.bytebuddy.dynamic.scaffold.TypeWriter$Default.make(TypeWriter.java:2224)
	at net.bytebuddy.dynamic.DynamicType$Builder$AbstractBase$UsingTypeWriter.make(DynamicType.java:4055)
	at net.bytebuddy.dynamic.DynamicType$Builder$AbstractBase.make(DynamicType.java:3739)
	at net.bytebuddy.dynamic.DynamicType$Builder$AbstractBase$Delegator.make(DynamicType.java:3991)
	at io.mockk.proxy.jvm.transformation.SubclassInstrumentation.doInterceptedSubclassing(SubclassInstrumentation.kt:83)
	at io.mockk.proxy.jvm.transformation.SubclassInstrumentation.subclass$lambda$0(SubclassInstrumentation.kt:53)
	at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:168)
	... 115 more

[milgner]

Update: it looks like I might have been too hasty in my assumption that everything works when basic the mock on the Impl class. Even though the mock setup doesn't produce any error, the answer is not being returned but instead it looks like the original implementation is invoked instead. Just like an unmocked extension function. I get the impression that the compiler might have treated the type-parameterized method similar to an extension function.

[thedanielhanke]

any news on this?