[testing] Order of execution of tests in TestNG

If you don't want to use the @Test(priority = ) option in TestNG, you can make use of the javaassist library and TestNG's IMethodInterceptor to prioritize the tests according to the order by which the test methods are defined in the test class. This is based on the solution provided here.

Add this listener to your test class:

package cs.jacob.listeners;

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;
import javassist.NotFoundException;

import org.testng.IMethodInstance;
import org.testng.IMethodInterceptor;
import org.testng.ITestContext;

public class PriorityInterceptor implements IMethodInterceptor {
    public List<IMethodInstance> intercept(List<IMethodInstance> methods, ITestContext context) {

    Comparator<IMethodInstance> comparator = new Comparator<IMethodInstance>() {
        private int getLineNo(IMethodInstance mi) {
        int result = 0;

        String methodName = mi.getMethod().getConstructorOrMethod().getMethod().getName();
        String className  = mi.getMethod().getConstructorOrMethod().getDeclaringClass().getCanonicalName();
        ClassPool pool    = ClassPool.getDefault();

        try {
            CtClass cc        = pool.get(className);
            CtMethod ctMethod = cc.getDeclaredMethod(methodName);
            result            = ctMethod.getMethodInfo().getLineNumber(0);
        } catch (NotFoundException e) {
            e.printStackTrace();
        }

        return result;
        }

        public int compare(IMethodInstance m1, IMethodInstance m2) {
        return getLineNo(m1) - getLineNo(m2);
        }
    };

    IMethodInstance[] array = methods.toArray(new IMethodInstance[methods.size()]);
    Arrays.sort(array, comparator);
    return Arrays.asList(array);
    }
}

This basically finds out the line numbers of the methods and sorts them by ascending order of their line number, i.e. the order by which they are defined in the class.