mockk: java.lang.NoClassDefFoundError: Could not initialize class androidx.lifecycle.LiveData$Subclass

Prerequisites

• I am running the latest version
• I checked the documentation and found no answer
• I checked to make sure that this issue has not already been filed

Expected Behavior

Unit tests that mock LiveData in a Robolectric unit test continue to function.

Current Behavior

What is the current behavior?

Mockk crashes. See referenced stacktrace below.

Failure Information (for bugs)

See issue reported to Robolectric: https://github.com/robolectric/robolectric/issues/5871

Steps to Reproduce

See sample project: https://github.com/zoubarry/TestApp

Context

• MockK version: 1.10.0
• OS: Mac OS 10.15.6
• Kotlin version: 1.3.72
• JDK version: openjdk8
• JUnit version: 4.12
• Type of test: unit test

Stack trace

java.lang.IllegalAccessError: tried to access class androidx.lifecycle.LiveData$ObserverWrapper from class androidx.lifecycle.LiveData$Subclass0

	at androidx.lifecycle.LiveData$Subclass0.<clinit>(Unknown Source)
	at sun.reflect.GeneratedSerializationConstructorAccessor5.newInstance(Unknown Source)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.objenesis.instantiator.sun.SunReflectionFactoryInstantiator.newInstance(SunReflectionFactoryInstantiator.java:48)
	at io.mockk.proxy.jvm.ObjenesisInstantiator.instanceViaObjenesis(ObjenesisInstantiator.kt:75)
	at io.mockk.proxy.jvm.ObjenesisInstantiator.instantiateViaProxy(ObjenesisInstantiator.kt:66)
	at io.mockk.proxy.jvm.ObjenesisInstantiator.instance(ObjenesisInstantiator.kt:29)
	at io.mockk.proxy.jvm.ProxyMaker.instantiate(ProxyMaker.kt:75)
	at io.mockk.proxy.jvm.ProxyMaker.proxy(ProxyMaker.kt:42)
	at io.mockk.impl.instantiation.JvmMockFactory.newProxy(JvmMockFactory.kt:34)
	at io.mockk.impl.instantiation.AbstractMockFactory.newProxy$default(AbstractMockFactory.kt:29)
	at io.mockk.impl.instantiation.AbstractMockFactory.temporaryMock(AbstractMockFactory.kt:127)
	at io.mockk.impl.recording.states.RecordingState$call$retValue$1.invoke(RecordingState.kt:72)
	at io.mockk.impl.instantiation.JvmAnyValueGenerator$anyValue$1.invoke(JvmAnyValueGenerator.kt:27)
	at io.mockk.impl.instantiation.AnyValueGenerator.anyValue(AnyValueGenerator.kt:27)
	at io.mockk.impl.instantiation.JvmAnyValueGenerator.anyValue(JvmAnyValueGenerator.kt:23)
	at io.mockk.impl.recording.states.RecordingState.call(RecordingState.kt:70)
	at io.mockk.impl.recording.CommonCallRecorder.call(CommonCallRecorder.kt:53)
	at io.mockk.impl.stub.MockKStub.handleInvocation(MockKStub.kt:263)
	at io.mockk.impl.instantiation.JvmMockFactoryHelper$mockHandler$1.invocation(JvmMockFactoryHelper.kt:25)
	at io.mockk.proxy.jvm.advice.Interceptor.call(Interceptor.kt:20)
	at com.example.testapp.MainViewModel.getData(MainViewModel.kt:13)
	at com.example.testapp.MainActivityTest$mockViewModel$1$1.invoke(MainActivityTest.kt:31)
	at com.example.testapp.MainActivityTest$mockViewModel$1$1.invoke(MainActivityTest.kt:24)
	at io.mockk.impl.eval.RecordedBlockEvaluator$record$block$1.invoke(RecordedBlockEvaluator.kt:24)
	at io.mockk.impl.eval.RecordedBlockEvaluator$enhanceWithNPERethrow$1.invoke(RecordedBlockEvaluator.kt:74)
	at io.mockk.impl.recording.JvmAutoHinter.autoHint(JvmAutoHinter.kt:23)
	at io.mockk.impl.eval.RecordedBlockEvaluator.record(RecordedBlockEvaluator.kt:36)
	at io.mockk.impl.eval.EveryBlockEvaluator.every(EveryBlockEvaluator.kt:30)
	at io.mockk.MockKDsl.internalEvery(API.kt:92)
	at io.mockk.MockKKt.every(MockK.kt:98)
	at com.example.testapp.MainActivityTest.<init>(MainActivityTest.kt:31)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:250)
	at org.robolectric.RobolectricTestRunner$HelperTestRunner.createTest(RobolectricTestRunner.java:561)
	at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:260)
	at org.junit.runners.BlockJUnit4ClassRunner$2.runReflectiveCall(BlockJUnit4ClassRunner.java:309)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:306)
	at org.robolectric.internal.SandboxTestRunner$HelperTestRunner.methodBlock(SandboxTestRunner.java:329)
	at org.robolectric.RobolectricTestRunner$HelperTestRunner.methodBlock(RobolectricTestRunner.java:570)
	at org.robolectric.internal.SandboxTestRunner$2.lambda$evaluate$0(SandboxTestRunner.java:259)
	at org.robolectric.internal.bytecode.Sandbox.lambda$runOnMainThread$0(Sandbox.java:89)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)

Minimal reproducible code (the gist of this issue)

@RunWith(AndroidJUnit4::class)
@Config(sdk = [28])
class MainActivityTest {
    @get:Rule
    val activityRule = ActivityTestRule(MainActivity::class.java, false, false)

    private val mockData = MutableLiveData<String>()

    private val mockViewModel = spyk(MainViewModel()) {
        every { data } returns mockData
        every { fetchData() } just Runs
    }

    @Test
    fun `robo livedata errors`() {
        activityRule.launchActivity(null)
        activityRule.activity.mainViewModel = mockViewModel
        mockData.value = "test"
    }
}