Post#126.Parallel Execution of test methods in TestNG

Parallel Execution of test methods in TestNG

TestNG provides multiple ways to execute tests in separate threads. In testng.xml, if we set 'parallel' attribute on the tag to 'tests', testNG will run all the ‘@Test’ methods in tag in the same thread, but each tag will be in a separate thread.

If we want to run methods/classes in separate threads, we need to set 'parallel' attribute on the tag to 'methods' / 'classes'

TestNG provides an ability to run test methods, test classes and tests in parallel. By using parallel execution, we can reduce the 'execution time' as tests are started and executed simultaneously in different threads.

**A thread is an independent path of execution within a program. Every thread in Java is created and controlled by the java.lang.Thread class.

Let’s Consider the below example:

package pack1;

import org.testng.annotations.Test;

public class ParallelTestId {

                                    @Test

                                    public void testCaseOne() {

                                               

                                                System.out.println("Test Case One with Thread Id:- "+ Thread.currentThread().getId());

                                    }

                                    @Test

                                    public void testCaseTwo() {

                                               

                                                System.out.println("Test Case two with Thread Id:- "+ Thread.currentThread().getId());

            }

}

If you will run the above program, you will get the output as below.

[TestNG] Running:

  C:\Users\Sujoy\AppData\Local\Temp\testng-eclipse-1521962657\testng-customsuite.xml

Test Case One with Thread Id:- 1

Test Case two with Thread Id:- 1

From the above output you can observe that both the test methods are running under one thread. i.e. Under Thread id 1

If you want to run independent test methods in multiple threads, then you have to configure your testng.xml file as below.

We are defining two attributes 'parallel' and 'thread-count' at suite level. As we want test methods to be executed in parallel, we have provided 'methods'. And 'thread-count' attribute is to use to pass the number of maximum threads to be created.

<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">

<suite name="Parallel test suite" parallel="methods" thread-count="2">

  <test name="Regression 1">

    <classes>

      <class name="pack1.ParallelTestId"/>

    </classes>

  </test>

</suite>

If you will run the above testng.xml file, you will get the output as below.

[TestNG] Running:

  E:\HardDisk\Sujoy\ SampleProject\testng.xml

Test Case One with Thread Id:- 11

Test Case two with Thread Id:- 12

The above result shows that two methods executed using different threads. When we run the same testng.xml again, the result may vary. The assigning of the thread is take care by the processor. So we can't say which thread is going to execute which method.