This class demonstrates on how to use AnnotationTransformer as a listener and inject group dependency on runtime. Here the problem statement is there are two classes AmDependent and AmIndependent. These two classes should be run sequentially but the test

AmDependent.java

import org.testng.annotations.Test;

@Test
public class AmDependent {
	public void methodD() {
		System.out.println(this.getClass().getSimpleName()
				+ ".method D : Thread ID : " + Thread.currentThread().getId());
		
	}

	public void methodE() {
		System.out.println(this.getClass().getSimpleName()
				+ ".method E : Thread ID : " + Thread.currentThread().getId());
	}

	public void methodF() {
		System.out.println(this.getClass().getSimpleName()
				+ ".method F : Thread ID : " + Thread.currentThread().getId());
	}
}

AmIndependent.java

import org.testng.annotations.Test;

@Test
public class AmIndependent {

	public void methodA() {
		System.out.println(this.getClass().getSimpleName()
				+ ".method A : Thread ID :" + Thread.currentThread().getId());

	}

	public void methodB() {
		System.out.println(this.getClass().getSimpleName()
				+ ". method B : Thread ID : " + Thread.currentThread().getId());
	}

	public void methodC() {
		System.out.println(this.getClass().getSimpleName()
				+ ". method C : Thread ID : " + Thread.currentThread().getId());
	}
}

GroupsDependencyRuntimeInjector.java

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

import org.testng.IAnnotationTransformer;
import org.testng.annotations.ITestAnnotation;

public class GroupsDependencyRuntimeInjector implements IAnnotationTransformer {
	public void transform(ITestAnnotation annotation, Class testClass,
			Constructor testConstructor, Method testMethod) {
		String []values = GroupTracker.getInstance().setDependency();
		String []groups = {values[0]};
		annotation.setGroups(groups);
		String []dependsOnGroups = {values[1]};
		dependsOnGroups[0] = values[1];
		if (!values[1].isEmpty())
			annotation.setDependsOnGroups(dependsOnGroups);
		System.out.println("Generated groupName = " + values[0]);
		System.out.println("Generated dependsOnGroupsName =" + values[1]);	
	}
}

GroupTracker.java

public class GroupTracker {
	private String groupName = null;
	private String dependsOnGroups = null;
	private String lastGroupName = null;
	private boolean isMasterGroupTaken = false;
	private static GroupTracker gp = null;
	private GroupTracker(){		
	}
	public static GroupTracker getInstance(){
		if (gp == null){
			gp = new GroupTracker();
			gp.groupName = "MasterGroup";
			gp.dependsOnGroups = "";
		}
		return gp;
	}
	public synchronized String[] setDependency(){
		String[]  returnValues = new String[2];
		if (isMasterGroupTaken){
			this.lastGroupName = groupName;
			groupName = "Group" + System.nanoTime();
			this.dependsOnGroups = this.lastGroupName;
		}
		if ("MasterGroup".equals(groupName)){
			this.isMasterGroupTaken = true;
		}
		returnValues[0] = groupName;
		returnValues[1] = dependsOnGroups;
		return returnValues;
	}
}

TestNG.xml

<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Suite" parallel="methods">
	<listeners>
		<listener class-name="mypackage.GroupsDependencyRuntimeInjector" />
	</listeners>
	<test name="Test">
		<packages>
			<package name="mypackage" />
		</packages>
	</test>
</suite>