Parallel testing of DataProviders in TestNG


The previous tutorial has explained the DataProviders in TestNG. The DataProvider in TestNG is a way to pass the parameters in the test functions. Using DataProvider in TestNG, we can easily inject multiple values into the same test case. It comes inbuilt into TestNG and is popularly used in data-driven frameworks.

 It is an option for the parallel execution of tests in TestNG. 

It is advisable to create 2 classes – one class contains the Test cases and another class defines TestNG parameters – DataProviders.

Let us create a class for the DataProvider method with all the Test Data as shown below:

import org.testng.annotations.DataProvider;

public class DataProviderDemo {	
	 @DataProvider(name = "testData", parallel=true)
	 public Object[][] dataProvFunc() {
	       return new Object[][] {           
	    	   {"","","Username cannot be empty"},    	  
	    	   {"","Test","Username cannot be empty"},
	    	   {"$%1234","2345%$","Invalid credentials"}          

An extra parameter “parallel” is required to initiate parallel execution in TestNG using the data provider.

Below is the test which uses the parameter from the data provider and runs the tests parallelly.

A new ThreadLocal is instantiated for each test class, since it’s in the BeforeClass annotation.

private static final ThreadLocal<WebDriver> WEB_DRIVER_THREAD_LOCAL = new ThreadLocal<WebDriver>();

Below is the complete test code:

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.testng.Assert;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;

public class DataProviderParallelTests {
	public WebDriver driver;
	private static final ThreadLocal<WebDriver> WEBDRIVER_THREADLOCAL = new ThreadLocal<WebDriver>();
    public void setUp(){

        driver = new ChromeDriver();
        System.out.println("Before method Thread Id:" + Thread.currentThread().getId());
	@Test(dataProvider = "testData", dataProviderClass = DataProviderDemo.class)
    public void invalidLoginTest(String username, String password, String errorMessage) throws InterruptedException {
	    driver = WEBDRIVER_THREADLOCAL.get();
        System.out.println("Username :" + username);
        System.out.println("password :" + password);
        String expectedError = driver.findElement("spanMessage")).getText();
        System.out.println("Error Message :" + expectedError);

	public void tear_down() {
		 WebDriver driver = WEBDRIVER_THREADLOCAL.get();
		 System.out.println("After method Thread Id:" + Thread.currentThread().getId());
	        if (driver != null) {


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "">
<suite name="Suite" thread-count="2" data-provider-thread-count="2">
  <test name="Test">
      <class name="DataProvider.DataProviderParallelTests"/>
  </test> <!-- Test -->
</suite> <!-- Suite -->

In this file, the data-provider-thread-count is set to 2, then two browsers will be opened, and the first two tests will run from the list. 

Run the test script from testng.xml, Right-Click on the XML, and select Run As ->TestNG Suite.

The execution status shown below shows that 2 threads are active at a time, which execute 2 sets of data provider parameters – Thread 14 and Thread 15. Once the tests are finished for Thread 14 and Thread 15, they are closed and a new Thread 15 is again initiated to start the test execution of the 3rd parameter.

TestNG generates multiple test reports under the folder test-output. We are mainly concerned about 2 reports – emailable-report.html and index.html.


Emailable reports are a type of summary report that one can transfer to other people in the team through any medium. 


Index report contains the index-like structure of different parts of the report, such as failed tests, test files, passed tests, etc. We can divide this report into two parts. The left part contains the index, and this is the reason it is called an index report, while the right part contains the explored content of that index.

We are done! Congratulations on making it through this tutorial and hope you found it useful! Happy Learning!!


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