Unit tests fail after kover is added to project

[josemssilva]

Describe the bug
After adding kover to the project, unit tests started failing for unexpected reasons. The issue seems related to MockK, however it isn't clear what is causing it, and it only happens once kover is integrated.

Errors

java.lang.UnsupportedOperationException: class redefinition failed: attempted to change the schema (add/remove fields)
	at java.instrument/sun.instrument.InstrumentationImpl.retransformClasses0(Native Method)
	at java.instrument/sun.instrument.InstrumentationImpl.retransformClasses(InstrumentationImpl.java:169)
	at io.mockk.proxy.jvm.transformation.JvmInlineInstrumentation.retransform(JvmInlineInstrumentation.kt:28)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation$doCancel$1.invoke(RetransformInlineInstrumentation.kt:38)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation$doCancel$1.invoke(RetransformInlineInstrumentation.kt:32)
	at io.mockk.proxy.common.transformation.ClassTransformationSpecMap.applyTransformation(ClassTransformationSpecMap.kt:41)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation.doCancel(RetransformInlineInstrumentation.kt:32)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation.access$doCancel(RetransformInlineInstrumentation.kt:6)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation$execute$1$1.invoke(RetransformInlineInstrumentation.kt:17)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation$execute$1$1.invoke(RetransformInlineInstrumentation.kt:17)
	at io.mockk.proxy.common.CancelableResult.cancel(CancelableResult.kt:22)
	at io.mockk.proxy.common.CancelableResult$alsoOnCancel$1.invoke(CancelableResult.kt:30)
	at io.mockk.proxy.common.CancelableResult$alsoOnCancel$1.invoke(CancelableResult.kt:29)
	at io.mockk.proxy.common.CancelableResult.cancel(CancelableResult.kt:22)
	at io.mockk.impl.instantiation.JvmConstructorMockFactory$ConstructorInvocationHandler.doCancel(JvmConstructorMockFactory.kt:242)
	at io.mockk.impl.instantiation.JvmConstructorMockFactory$ConstructorInvocationHandler.access$doCancel(JvmConstructorMockFactory.kt:155)
	at io.mockk.impl.instantiation.JvmConstructorMockFactory$ConstructorInvocationHandler$push$2.invoke(JvmConstructorMockFactory.kt:217)
	at io.mockk.impl.instantiation.JvmConstructorMockFactory$ConstructorInvocationHandler$push$2.invoke(JvmConstructorMockFactory.kt:216)
	at io.mockk.MockKCancellationRegistry$RegistryPerType.cancelAll(API.kt:2440)
	at io.mockk.MockKCancellationRegistry.cancelAll(API.kt:2469)

Expected behavior
Tests shouldn't fail, as it was happening prior to introducing kover.

Reproducer
Only happens in test classes, when unmockkAll() is called.

Reports

Environment

• Kover Gradle Plugin version: 0.9.1
• Gradle version: 8.6
• Kotlin project type: Kotlin/Android
• Coverage Toolset (if customized in build script): -
• Other context important for this bug: -

[shanshin]

Hi,
is this a complete error stack trace?

Don't you have a small production project? Due to this error, it is difficult to understand which instrumentation class is causing the error.

[josemssilva]

Full stacktrace:

java.lang.UnsupportedOperationException: class redefinition failed: attempted to change the schema (add/remove fields)
	at java.instrument/sun.instrument.InstrumentationImpl.retransformClasses0(Native Method)
	at java.instrument/sun.instrument.InstrumentationImpl.retransformClasses(InstrumentationImpl.java:169)
	at io.mockk.proxy.jvm.transformation.JvmInlineInstrumentation.retransform(JvmInlineInstrumentation.kt:28)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation$doCancel$1.invoke(RetransformInlineInstrumentation.kt:38)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation$doCancel$1.invoke(RetransformInlineInstrumentation.kt:32)
	at io.mockk.proxy.common.transformation.ClassTransformationSpecMap.applyTransformation(ClassTransformationSpecMap.kt:41)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation.doCancel(RetransformInlineInstrumentation.kt:32)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation.access$doCancel(RetransformInlineInstrumentation.kt:6)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation$execute$1$1.invoke(RetransformInlineInstrumentation.kt:17)
	at io.mockk.proxy.common.transformation.RetransformInlineInstrumentation$execute$1$1.invoke(RetransformInlineInstrumentation.kt:17)
	at io.mockk.proxy.common.CancelableResult.cancel(CancelableResult.kt:22)
	at io.mockk.proxy.common.CancelableResult$alsoOnCancel$1.invoke(CancelableResult.kt:30)
	at io.mockk.proxy.common.CancelableResult$alsoOnCancel$1.invoke(CancelableResult.kt:29)
	at io.mockk.proxy.common.CancelableResult.cancel(CancelableResult.kt:22)
	at io.mockk.impl.instantiation.JvmConstructorMockFactory$ConstructorInvocationHandler.doCancel(JvmConstructorMockFactory.kt:242)
	at io.mockk.impl.instantiation.JvmConstructorMockFactory$ConstructorInvocationHandler.access$doCancel(JvmConstructorMockFactory.kt:155)
	at io.mockk.impl.instantiation.JvmConstructorMockFactory$ConstructorInvocationHandler$push$2.invoke(JvmConstructorMockFactory.kt:217)
	at io.mockk.impl.instantiation.JvmConstructorMockFactory$ConstructorInvocationHandler$push$2.invoke(JvmConstructorMockFactory.kt:216)
	at io.mockk.MockKCancellationRegistry$RegistryPerType.cancelAll(API.kt:2440)
	at io.mockk.MockKCancellationRegistry.cancelAll(API.kt:2469)
	at packagename.classname.finish(TestClass.kt:857)
	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:569)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
	at org.junit.internal.runners.statements.RunAfters.invokeMethod(RunAfters.java:46)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:33)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
	at jdk.internal.reflect.GeneratedMethodAccessor88.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:569)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
	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)

It's really odd, because it only fails when running via CLI. Also, when doing sequential tests it only fails the first run (then it fails again after a ./gradlew clean).

[shanshin]

Is your project multi-module?

You may limit instrumented classes in all projects.
To do this, specify this setting in each project:

kover {
    currentProject {
        instrumentation {
            excludedClasses.add("io.mockk.*")
        }
    }
}

If it doesn't help, try to instrument the classes of your application only. To do this, specify the largest package in which all your classes are exactly located (in include filter)

kover {
    currentProject {
        instrumentation {
            includedClasses.add("com.myapplication.*")
        }
    }
}

[josemssilva]

Yes, multi-module.

None of the solutions worked, unfortunately. However, I was able to solve it by replacing unmockkAll() with unmockkStatic() for each of the mockkStatic() previously performed. I still can't find a reason for it to fail with the former, and it was odd that it only happened after integration Kover, so I thought it could be an issue with the tool.

Sorry for the mess, I believe we can now close this.

[shanshin]

OK, but please reopen the issue if you create a small stable reproducer.