Error with setInternalState and JDK12 "java.lang.NoSuchFieldException: modifiers"

[eolivelli]

What steps will reproduce the problem?
Use WhiteBox#setInternalState with JDK12

What is the expected output?
setInternalState does not throw exception

What do you see instead?

java.lang.RuntimeException: Internal error: Failed to find the "modifiers" field in method setInternalState.
	at org.powermock.reflect.internal.WhiteboxImpl.sedModifiersToField(WhiteboxImpl.java:2354)
	at org.powermock.reflect.internal.WhiteboxImpl.removeFinalModifierIfPresent(WhiteboxImpl.java:2318)
	at org.powermock.reflect.internal.WhiteboxImpl.setField(WhiteboxImpl.java:2304)
	at org.powermock.reflect.internal.WhiteboxImpl.setInternalState(WhiteboxImpl.java:304)
	at org.powermock.reflect.internal.WhiteboxImpl.setInternalState(WhiteboxImpl.java:317)
	at org.powermock.reflect.Whitebox.setInternalState(Whitebox.java:190)
	at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:61)
	at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:365)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeWithRerun(JUnit4Provider.java:273)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:238)
	at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:159)

What version of the product are you using?
2.0.0.Beta5

[eolivelli]

Anyone else has this problem ?
Is there any workaround ?

[ijuma]

OpenJDK discussion: http://mail.openjdk.java.net/pipermail/core-libs-dev/2018-November/056486.html

[eolivelli]

Thank you @ijuma for posting my discussion.
I will try the approach suggested by Alan.
If it is interesting I can share my trials woth powermock community.
It is blocker for me for jdk12 adoption

[eolivelli]

@ijuma this is my proof of concept, it is a very simple agent made with ByteBuddy.
https://github.com/eolivelli/tweakjava

It works for most of the cases, but in the case he specific error at at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:61)

It does not work because ByteBuddy is not "transforming" the Annotation[] fAnnotations field of org.junit.runner.Description.

It seems a bug in ByteBuddy (raphw/byte-buddy#559).

That specific case, could be worked-around in PowerMock by just not failing in case of failure in that point in the finally block. In that case there is a best-effort trial to reset a field in description.

Temporary you can bypass the specific error with a subclass of PowerMockRunner, this is very hacky but 'it works'

public class SafePowerMockRunner extends PowerMockRunner {

    public SafePowerMockRunner(Class<?> klass) throws Exception {
        super(klass);
    }

    @Override
    public void run(RunNotifier notifier) {
        try {
            super.run(notifier);
        } catch (RuntimeException err) {
            if (err.getCause() instanceof java.lang.NoSuchFieldException
                    && err.getCause().getMessage().equals("modifiers")) {
                // on JDK12 you cannot change 'modifiers'
            } else {
                throw err;
            }
        }
    }

}

[eolivelli]

For org.powermock.modules.junit4.PowerMockRunner I think we should have a minimal fix which ignores the error. I can send a patch

[eolivelli]

This is my minimal patch
#955

[rnveach]

Fix in PR only suppresses exception in one part of powermock's own code but if users call Whitebox.setInternalState on a final field themselves they will still get the exception.
There is no alternative way to accomplish this task when using Java 12?

[eolivelli]

@rnveach you can use a java agent like this one https://github.com/eolivelli/tweakjava

[ghost]

Unsafe.putObject(base, offset, value) works fine under Java 12.

[Vampire]

There are multiple ways.
There are a bunch of classes for which fields are filtered now when using Class#getDeclaredFields.

• But you can either use yet another private API and use the method Class#getDeclaredFields0(false) to get the unfiltered list and pick the wanted field from there,
• Or you can use Unsafe.putObject
• Or you can use VarHandles and MethodHandles.privateLookupIn()
  The latter probably being the most "appropriate" to do unappropriate things, as it is the only official API.