Mockk: Caused by: io.mockk.MockKException: Failed to load plugin. io.mockk.proxy.jvm.JvmMockKAgentFactory

[lecin]

Prerequisites

Please answer the following questions for yourself before submitting an issue.

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

Expected Behavior

AndroidX JVM unit tests passed successfully.

Current Behavior

Test failed when the test run on JVM.
It is a success on a real device.

Failure Information (for bugs)

Steps to Reproduce

Please provide detailed steps for reproducing the issue.

1. Test run on Android Studio using Gradle task (Tasks - verification - test)
2. Test failed with ClassNotFoundException
   (Works fine with "connectedAndroidTest")

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: Android 1.9.3
• OS: MacOS 10.14.5
• Kotlin version: 1.3.31
• JDK version: JAVA_VERSION="1.8.0_152" (Android Studio embedded)
• JUnit version: 4.12
• Type of test: unit test of Espresso UI test (AndroidX)

Stack trace

java.lang.Exception: Main looper has queued unexecuted runnables. This might be the cause of the test failure. You might need a shadowOf(getMainLooper()).idle() call.
    at org.robolectric.android.internal.AndroidTestEnvironment.checkStateAfterTestFailure(AndroidTestEnvironment.java:470)
    at org.robolectric.RobolectricTestRunner$HelperTestRunner$1.evaluate(RobolectricTestRunner.java:548)
    at org.robolectric.internal.SandboxTestRunner$2.lambda$evaluate$0(SandboxTestRunner.java:252)
    at org.robolectric.internal.bytecode.Sandbox.lambda$runOnMainThread$0(Sandbox.java:89)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ExceptionInInitializerError
    at // remove package name
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at "packagename".MockWebServerRule$apply$1.evaluate(MockWebServerRule.kt:22)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    at org.robolectric.RobolectricTestRunner$HelperTestRunner$1.evaluate(RobolectricTestRunner.java:546)
    ... 6 more
Caused by: io.mockk.MockKException: Failed to load plugin. io.mockk.proxy.jvm.JvmMockKAgentFactory Check if you included 'io.mockk:mockk-android' dependency instead of 'io.mockk:mockk'
    at io.mockk.impl.JvmMockKGateway.<init>(JvmMockKGateway.kt:186)
    at io.mockk.impl.JvmMockKGateway.<clinit>(JvmMockKGateway.kt:172)
    ... 20 more
Caused by: java.lang.ClassNotFoundException: io.mockk.proxy.jvm.JvmMockKAgentFactory
    at org.robolectric.internal.bytecode.SandboxClassLoader.getByteCode(SandboxClassLoader.java:164)
    at org.robolectric.internal.bytecode.SandboxClassLoader.maybeInstrumentClass(SandboxClassLoader.java:119)
    at org.robolectric.internal.bytecode.SandboxClassLoader.lambda$findClass$0(SandboxClassLoader.java:112)
    at org.robolectric.util.PerfStatsCollector.measure(PerfStatsCollector.java:53)
    at org.robolectric.internal.bytecode.SandboxClassLoader.findClass(SandboxClassLoader.java:111)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at io.mockk.impl.JvmMockKGateway.<init>(JvmMockKGateway.kt:184)
    ... 21 more

Minimal reproducible code (the gist of this issue)

// objenesis exclusion for workaround in mockk 1.9.3 (https://github.com/mockk/mockk/issues/281)
    testImplementation("io.mockk:mockk-android:1.9.3") {
        exclude(module = "objenesis")
    }
    testImplementation("org.objenesis:objenesis:2.6")
//////
    fun inputAmount_startPayment() {
        val navController = mockk<NavController>(relaxed = true)
        ....
    }

[stale[bot]]

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[oleksiyp]

So here seems to be an issue with linking another dependency.

The exception says what is wrong:

Check if you included 'io.mockk:mockk-android' dependency instead of 'io.mockk:mockk'

So for unit tests io.mockk:mockk should be used and for Android Instrumented tests io.mockk:mockk-android