unit testing - AttachNotSupportedException while running jMockit tests on IBM JRE

Question

I am getting the below exception when I try to run a simple jMockit/JUnit test using IBM JDK. Has anyone faced this issue? I tried given -Dcom.ibm.tools.attach.enable=yes as VM argument but no luck. The same code is working fine in Sun JDK.

java.lang.RuntimeException: com.sun.tools.attach.AttachNotSupportedException: Unable to enqueue operation: the target VM does not support attach mechanism
    at mockit.internal.startup.JDK6AgentLoader.getVirtualMachineImplementationFromEmbeddedOnes(JDK6AgentLoader.java:89)
    at mockit.internal.startup.JDK6AgentLoader.loadAgent(JDK6AgentLoader.java:54)
    at mockit.internal.startup.AgentInitialization.initializeAccordingToJDKVersion(AgentInitialization.java:21)
    at mockit.internal.startup.Startup.initializeIfNeeded(Startup.java:98)
    at mockit.internal.startup.Startup.initializeIfPossible(Startup.java:112)
    at org.junit.runner.Runner.<clinit>(Runner.java:22)
    at java.lang.J9VMInternals.initializeImpl(Native Method)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:200)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:167)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:167)
    at org.junit.internal.builders.JUnit4Builder.runnerForClass(JUnit4Builder.java:13)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
    at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:29)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
    at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:24)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.<init>(JUnit4TestReference.java:33)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestClassReference.<init>(JUnit4TestClassReference.java:25)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:48)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:452)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: com.sun.tools.attach.AttachNotSupportedException: Unable to enqueue operation: the target VM does not support attach mechanism
    at sun.tools.attach.WindowsVirtualMachine.<init>(WindowsVirtualMachine.java:64)
    at mockit.internal.startup.JDK6AgentLoader.getVirtualMachineImplementationFromEmbeddedOnes(JDK6AgentLoader.java:73)
    ... 22 more
java.lang.NoClassDefFoundError: org.junit.internal.runners.ErrorReportingRunner (initialization failure)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:140)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
    at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:24)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.<init>(JUnit4TestReference.java:33)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestClassReference.<init>(JUnit4TestClassReference.java:25)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:48)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:452)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.NoClassDefFoundError: org.junit.runner.Runner (initialization failure)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:140)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:167)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
    at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:29)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
    ... 9 more
Caused by: java.lang.RuntimeException: com.sun.tools.attach.AttachNotSupportedException: Unable to enqueue operation: the target VM does not support attach mechanism
    at mockit.internal.startup.JDK6AgentLoader.getVirtualMachineImplementationFromEmbeddedOnes(JDK6AgentLoader.java:89)
    at mockit.internal.startup.JDK6AgentLoader.loadAgent(JDK6AgentLoader.java:54)
    at mockit.internal.startup.AgentInitialization.initializeAccordingToJDKVersion(AgentInitialization.java:21)
    at mockit.internal.startup.Startup.initializeIfNeeded(Startup.java:98)
    at mockit.internal.startup.Startup.initializeIfPossible(Startup.java:112)
    at org.junit.runner.Runner.<clinit>(Runner.java:22)
    at java.lang.J9VMInternals.initializeImpl(Native Method)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:200)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:167)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:167)
    at org.junit.internal.builders.JUnit4Builder.runnerForClass(JUnit4Builder.java:13)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
    ... 11 more
Caused by: com.sun.tools.attach.AttachNotSupportedException: Unable to enqueue operation: the target VM does not support attach mechanism
    at sun.tools.attach.WindowsVirtualMachine.<init>(WindowsVirtualMachine.java:64)
    at mockit.internal.startup.JDK6AgentLoader.getVirtualMachineImplementationFromEmbeddedOnes(JDK6AgentLoader.java:73)
    ... 22 more

I tried giving the VM argument -javaagent:jmockit.jar as suggested by Kevin Welker and I got the below exception.

Exception in thread "main" java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
    at java.lang.reflect.Method.invoke(Method.java:600)
    at sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:335)
    at sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:350)
Caused by: java.lang.NullPointerException
    at mockit.internal.annotations.MockClassSetup.validateRealClass(MockClassSetup.java:59)
    at mockit.internal.annotations.MockClassSetup.<init>(MockClassSetup.java:38)
    at mockit.internal.annotations.MockClassSetup.<init>(MockClassSetup.java:77)
    at mockit.internal.annotations.MockClassSetup.<init>(MockClassSetup.java:99)
    at mockit.internal.startup.JMockitInitialization.setUpInternalStartupMock(JMockitInitialization.java:56)
    at mockit.internal.startup.JMockitInitialization.initialize(JMockitInitialization.java:29)
    at mockit.internal.startup.Startup.initialize(Startup.java:68)
    at mockit.internal.startup.Startup.premain(Startup.java:56)
    ... 6 more

Fatal error: processing of -javaagent failed

Answer 1

The Attach API simply doesn't work in the IBM JDK 6.0, at least on Windows. Therefore, it's necessary to use the -javaagent:jmockit.jar parameter.

The NullPointerException that occurs at MockClassSetup.java:59, when using -javaagent, is caused by a bug in the IBM JDK. When a type referenced in an annotation attribute (@MockClass, in this case) is not present in the classpath, the JDK should throw a TypeNotPresentException. The Oracle JDKs do so as expected, but the IBM JDK returns null instead for the attribute value.

I just implemented a workaround for this in class MockClassSetup, which will be available in the next JMockit release, by the end of september. For now, you can avoid the problem by adding TestNG to the classpath (since the "type not found" is the org.testng.TestNG class).