IllegalClassFormatException when using JaCoCo with JMockit

Jim Anderson

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Sep 20, 2012, 1:20:02 PM9/20/12

to jac...@googlegroups.com

I'm getting an IllegalClassFormatException when running tests with jacoco, when the class under test creates an instance of a class that is mocked by the test. Here's a simple example:

public class Counter {

// Counter2 will be mocked by the test!

private static Counter2 counter2;

static {

System.out.println("in static initializer of Counter!");

counter2 = new Counter2();

}

public Integer addOne(Integer input) {

System.out.println("in Counter.addOne");

return ++input;

}

public Integer addTwo(Integer input) {

return input + 2;

}

public class Counter2 {

public Integer addFive(Integer num) {

return num + 5;

}

public class TestCounter {

@Before

public void setUp() {

Mockit.setUpMock(MockCounter.class);

Mockit.setUpMock(MockCounter2.class);

System.out.println("in TestCounter.setup");

}

@After

public void tearDown() {

System.out.println("in TestCounter.teardown");

Mockit.tearDownMocks();

}

@Test

public void testAdd() {

System.out.println("in TestCounter.testAdd");

Counter c = new Counter();

assertEquals((Integer) 3, c.addOne(2));

}

@MockClass(realClass = Counter.class)

public static class MockCounter {

public static Integer num = new Integer(1);

@Mock

public Integer addTwo(Integer input) {

System.out.println("in mocked addTwo!!!!!");

return new Integer(1);

}

@MockClass(realClass = Counter2.class)

public static class MockCounter2 {

@Mock

public Integer addFive(Integer num) {

System.out.println("in MockCounter2.addFive");

return new Integer(5);

}

This is the output including the stack trace:

[jacoco:coverage] Enhancing junit with coverage

[junit] Testsuite: TestCounter

[junit] Tests run: 1, Failures: 0, Errors: 0, Time elapsed: 0.716 sec

[junit]

[junit] ------------- Standard Output ---------------

[junit] in static initializer of Counter!

[junit] in TestCounter.setup

[junit] in TestCounter.testAdd

[junit] in Counter.addOne

[junit] in TestCounter.teardown

[junit] ------------- ---------------- ---------------

[junit] ------------- Standard Error -----------------

[junit] java.lang.instrument.IllegalClassFormatException: Error while instrumenting class Counter2.

[junit] at org.jacoco.agent.rt_plkeqq.CoverageTransformer.transform(CoverageTransformer.java:94)

[junit] at sun.instrument.TransformerManager.transform(TransformerManager.java:188)

[junit] at sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:424)

[junit] at sun.instrument.InstrumentationImpl.redefineClasses0(Native Method)

[junit] at sun.instrument.InstrumentationImpl.redefineClasses(InstrumentationImpl.java:170)

[junit] at mockit.internal.RedefinitionEngine.redefineMethods(RedefinitionEngine.java:244)

[junit] at mockit.internal.RedefinitionEngine.redefineMethods(RedefinitionEngine.java:238)

[junit] at mockit.internal.RedefinitionEngine.redefineMethods(RedefinitionEngine.java:166)

[junit] at mockit.internal.RedefinitionEngine.redefineMethods(RedefinitionEngine.java:159)

[junit] at mockit.Mockit.setUpMock(Mockit.java:425)

[junit] at TestCounter.setUp(TestCounter.java:13)

[junit] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

[junit] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

[junit] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

[junit] at java.lang.reflect.Method.invoke(Method.java:601)

[junit] at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)

[junit] at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)

[junit] at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)

[junit] at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)

[junit] at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:30)

[junit] at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)

[junit] at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)

[junit] at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)

[junit] at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)

[junit] at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)

[junit] at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)

[junit] at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)

[junit] at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)

[junit] at org.junit.runners.ParentRunner.run(ParentRunner.java:300)

[junit] at junit.framework.JUnit4TestAdapter.run(JUnit4TestAdapter.java:39)

[junit] at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.run(JUnitTestRunner.java:520)

[junit] at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.launch(JUnitTestRunner.java:1060)

[junit] at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.main(JUnitTestRunner.java:911)

[junit] Caused by: java.lang.NoSuchFieldException: $jacocoData

[junit] at java.lang.Class.getDeclaredField(Class.java:1899)

[junit] at org.jacoco.agent.rt_plkeqq.core.runtime.AbstractRuntime.disconnect(AbstractRuntime.java:88)

[junit] at org.jacoco.agent.rt_plkeqq.CoverageTransformer.transform(CoverageTransformer.java:90)

[junit] ... 32 more