NoClassDefFound test error with Jacoco

[Vincent Massol]

Hi guys,

I'm trying out Jacoco on some maven project. This project builds fine when I don't have Jacoco in the project but as soon as I have it my tests fail with on some third party dep I'm using (PircBotX):

…
Caused by: java.lang.ArrayIndexOutOfBoundsException: 0
        at org.pircbotx.hooks.ListenerAdapter.<clinit>(ListenerAdapter.java:106)
…

I've checked the source code and line 106 is:

Class<?> curClass = curMethod.getParameterTypes();

in:
…
static {
//Map events to methods
for (Method curMethod : ListenerAdapter.class.getDeclaredMethods()) {
if (curMethod.getName().equals("onEvent"))
continue;
Class<?> curClass = curMethod.getParameterTypes();
if (!curClass.isInterface()) {
Set methods = new HashSet();
methods.add(curMethod);
eventToMethod.put((Class<? extends Event>) curClass, methods);
}
}
…

So it seems Jacoco's instrumentation is messing something up but since I don't know what code Jacoco injects I have no clue what the problem can be.

Any idea?

Thanks a lot
-Vincent

[Vincent Massol]

Note: Sorry about the title of this issue. I thought the problem was a NoClassDefFoundError initially but I think the root cause is instead this ArrayIndexOutOfBoundsException I reported above.

[Vincent Massol]

ok found the problem I think. I was able to see that the method that generates the problem is:

private static final boolean org.pircbotx.hooks.ListenerAdapter.$jacocoInit()

So the issue is that the PircBotX project has some code that is not well protected against problems…

I'll read up to find a way to exclude this class from instrumentation

[Vincent Massol]

ok I found it and it works :)

For the record:

      <plugin>
        <groupId>org.jacoco</groupId>
        <artifactId>jacoco-maven-plugin</artifactId>
        <version>0.5.6.201201232323</version>
        <configuration>
          <destfile>${basedir}/target/coverage-reports/jacoco-unit.exec</destfile>
          <datafile>${basedir}/target/coverage-reports/jacoco-unit.exec</datafile>
          <excludes>
            <exclude>org.pircbotx.hooks.ListenerAdapter</exclude>
          </excludes>
        </configuration>
…

[Marc R. Hoffmann]

Your analysis is correct. JaCoCo adds two members to instrumented classes:

- static field $jacocoData
- static method $jacocoInit

Both members have the modifiers private and synthetic. So frameworks really shouldn't touch such members.