What is Parallel Testing?
Parallelism or multi-threading in software terms is defined as the ability of the software, operating system, or program to execute multiple parts or sub-components of another program simultaneously.
Parallel testing helps to reduce execution time and efforts and results in faster time to delivery. In a scenario where we have two versions of software available, and we need to check its stability and compatibility, we can run the two versions simultaneously and find issues at a much faster rate.
How to run Parallel Tests with Selenium
TestNG provides multiple ways to execute tests in separate threads. In testng.xml, if we set ‘parallel’ attribute on the tag to ‘methods’, testNG will run all the ‘@Test’ methods in tag in a separate thread.
The project Structure looks like shown below:-
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="TestSuite" thread-count="3" parallel="methods" >
<test name="GoogleTest">
<classes>
<class name="TestNGDemo.ParallelTestDemo">
</class>
</classes>
</test>
</suite>
The attribute thread-count allows you to specify how many threads should be allocated for this execution.
parallel = “methods” means that the methods will run parallel
The parallel attribute can be extended for multiple values, as below:
· Methods: Helps run methods in separate threads
· Tests: Help to run all methods belonging to the same tag in the same thread, means tests will run sequentially
· Classes: Helps to run all methods belonging to a class in a single thread
· Instances: Helps run all methods in the same instance in the same thread
How to run Tests parallel
Right click on TestNG.xml and Run AS TestNG Suite. If you will run the Test Class – ParallelTestDemo.java as Right click and then Run As TestNG Tests, then the methods will run sequentially.
In this Example, three test cases or methods will run parallel and enter search word like TestNG Framework, Maven, and Selenium WebDriver in Google.
import org.openqa.selenium.By;
import org.openqa.selenium.Keys;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
import org.testng.annotations.Test;
public class ParallelTestDemo {
@Test
public void executSessionOne() {
System.setProperty("webdriver.chrome.driver",
"C:\\Users\\Vibha\\Desktop\\Drivers\\chromedriver_win32\\chromedriver.exe");
WebDriver driver = new ChromeDriver();
// Goto google site
driver.get("https://www.google.com/ ");
// enter word in search box
WebElement Element1 = driver.findElement(By.name("q"));
Element1.sendKeys("Selenium WebDriver");
Element1.sendKeys(Keys.ENTER);
System.out.println("Test Case One with Thread Id:-"+Thread.currentThread().getId());
}
@Test
public void executeSessionTwo() {
// Second session of WebDriver
System.setProperty("webdriver.chrome.driver",
"C:\\Users\\Vibha\\Desktop\\Drivers\\chromedriver_win32\\chromedriver.exe");
WebDriver driver = new ChromeDriver();
// Goto google site
driver.get("https://www.google.com/ ");
// enter word in search box
WebElement Element2 = driver.findElement(By.name("q"));
Element2.sendKeys("TestNG Framework");
Element2.sendKeys(Keys.ENTER);
System.out.println("Test Case Two with Thread Id:-"+Thread.currentThread().getId());
}
@Test
public void executSessionThree() {
// Third session of WebDriver
System.setProperty("webdriver.chrome.driver",
"C:\\Users\\Vibha\\Desktop\\Drivers\\chromedriver_win32\\chromedriver.exe");
WebDriver driver = new ChromeDriver();
// Goto google site
driver.get("https://www.google.com/ ");
// enter word in search box
WebElement Element3 = driver.findElement(By.name("q"));
Element3.sendKeys("Maven");
Element3.sendKeys(Keys.ENTER);
System.out.println("Test Case Three with Thread Id:-"+Thread.currentThread().getId());
}
}
Output
Test Case Three with Thread Id:- 14
Test Case Two with Thread Id:- 15
Test Case One with Thread Id:- 13
===============================================
TestSuite
Total tests run: 3, Passes: 3, Failures: 0, Skips: 0
===============================================
TestNG Report – Go to test-output folder and open emailable-report.html
Run Tests Sequentially
If you will run the Test Class – ParallelTestDemo.java as Right click and then Run As TestNG Tests, then the methods will run sequentially. Here all tests are run with Thread 1 whereas with parallel execution tests were run with different threads.
We can make parallel = none, if don’t want to run them parallel.
<suite name="TestSuite" thread-count="3" parallel="none" >
QA Automation Expert 
It's quite informative..can you help with how to prioritize test cases while running..
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Thanks Abha. There will be a separate blog on prioritizing the test cases using TestNG. Will keep you posted
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how can i disable some of my test cases in testng. i don't want to delete them… Thanks for your help in advance
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Hi, we can disable test cases in TestNG. There is parameter like @Test(enabled = false) which will disable the execution of tests in TestNG. For more detail, can refer – https://configureselenium.blogspot.com/2020/02/how-to-disable-selenium-test-cases.html
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