accessing test classes from javaagent using maven-surefire - instrumentation

Question

I am trying to run an analysis that would capture the values of the locator when running selenium test. Having a large number of projects and versions to test, I want to avoid directly modifying the project files whatsoever, hence, I resorted to the use of a javaagent (with ByteBuddy). The idea is to instrument the test classes so they will get me the information I need. Hence, in the pom.xml of the project I am analyzing i had to setup the surefire-plugin as follow
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>3.0.0-M1</version>
<configuration>
<argLine>#{argLine} -javaagent:\path\to\my\agent.jar</argLine>
<forkCount>0</forkCount>
</configuration>
</plugin>
The argLine field allows me to attach the agent to the surefire process and the forkCount forces surefire to only use one JVM which should allow me to have a visibility on all the classes that are loaded (I think).
As for the agent, I have the premain method as follow
public static void premain(final String agentArgs,
final Instrumentation inst) {
System.out.println("Starting to collect metrics");
new AgentBuilder.Default()
.with(new AgentBuilder.InitializationStrategy.SelfInjection.Eager())
.type(ElementMatchers.any())
.transform(new LocatorReporterTransformer())
.with(AgentBuilder.TypeStrategy.Default.REDEFINE)
.installOn(inst);
}
I used the ElementMatchers.any() to be sure to be able to see all the classes that were intercepted by my agent. In the LocatorReporterTransormer class, i have the method transform(...) as follow
#Override
public DynamicType.Builder<?> transform(DynamicType.Builder<?> builder,
TypeDescription typeDescription,
ClassLoader classLoader,
JavaModule javaModule) {
System.out.println(typeDescription.getName());
return builder;
}
My goal was to capture some of the classes from my tests, but it seems they are never loaded in the JVM, which is weird to me. Thus, my question is: How can I safeley add a javaagent to surefire and make sure it can access all the classes? Is there a way for the javaagent to capture all the subprocess from a target?

Answer 1

The classes were not all visible because more than one process was executing. It seems that the forkCount = 0 d did not do the trick. One solution is to actually attach the agent on the maven process using the MAVEN_OPTS and then use fockMode = never. Here is the implementation that works in my case:
set "MAVEN_OPTS=-javaagent:\path\to\agent.jar"
mvn test -DforkMode=never