Code Coverage: Cobertura, and Testing Load-time Weaving with Maven

Our cassandra-triggers implementation uses AOP. Virgil also uses it for connection pooling and retries. More specifically, each of these projects uses load-time weaving, where the byte code of the classes is changed at runtime. For testing purposes, we have the following added to our pom file:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.9</version>
    <configuration>
    <argLine>-javaagent:lib/aspectjweaver.jar</argLine>
    </configuration>
</plugin>

This adds the aspectjweaver agent to the jvm runtime, which enables and performs the load-time weaving. When we went to gather code coverage information on the projects, we ended up with the following exception out of aspectj.

[IsolatedClassLoader@1342ba4] warning register definition failed -- (BCException) malformed class file
malformed class file
org.aspectj.weaver.BCException: malformed class file
 at org.aspectj.weaver.bcel.Utility.makeJavaClass(Utility.java:466)
 at org.aspectj.weaver.bcel.BcelWeaver.addLibraryAspect(BcelWeaver.java:189)

Evidently, aspectj doesn't like cobertura instrumented classes. After much googling, I couldn't find a good solution. There appeared to be a lot of back and forth between cobertura and aspectj. To avoid the situation entirely, I simply decided to maintain to pom files. I swapped out the plugin above that adds the agent jvm, for the snippet below that enables compile-time weaving:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>aspectj-maven-plugin</artifactId>
    <version>1.4</version>
    <configuration>
        <complianceLevel>1.5</complianceLevel>
        <weaveDependencies>
            <weaveDependency>
                <groupId>org.apache.cassandra</groupId>
                <artifactId>cassandra-thrift</artifactId>
            </weaveDependency>
            <weaveDependency>
                <groupId>org.apache.cassandra</groupId>
                <artifactId>cassandra-all</artifactId>
            </weaveDependency>
        </weaveDependencies>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>compile</goal>
            </goals>
        </execution>
    </executions>
</plugin>

This swaps from load-time weaving during testing to the compile-time weaving, which allows cobertura and aspectj to play well together, which means you'll get accurate code coverage numbers in Sonar.