How to configure maven surefire to use an jvm agent that is a dependency?

I would like to configure the maven sure fire plugin to start the unit testing jvm with the argument for a java agent. The agent jar file is being obtained from maven central so I want maven to automatically figure out the path to the agent's jar file.

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.12.4</version>
    <configuration>
        <argLine>-javaagent: How to reference an agent jar that is a depedency </argLine>
    </configuration>
</plugin>

How can I refer to the path to the agent which is a dependency of the project using maven co-ordinates?

Solution

You can copy one of your needed jars to a target destination. Then refer to that jar on your command line.

Here is an example (using log4j which is NOT a valid agent jar but just to show an example):

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-dependency-plugin</artifactId>
    <version>2.5.1</version>
    <executions>
        <execution>
            <id>copy-agent</id>
            <phase>process-test-classes</phase>
            <goals>
                <goal>copy</goal>
            </goals>
            <configuration>
                <artifactItems>
                    <artifactItem>
                        <groupId>log4j</groupId>
                        <artifactId>log4j</artifactId>
                        <version>1.2.14</version>
                        <outputDirectory>${project.build.directory}/agents</outputDirectory>
                        <destFileName>my-special-agent.jar</destFileName>
                    </artifactItem>
                </artifactItems>
            </configuration>
        </execution>
    </executions>
</plugin>
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.12.4</version>
    <configuration>
        <argLine>-javaagent:${project.build.directory}/agents/my-special-agent.jar</argLine>
    </configuration>
</plugin>