Parallel testing with DataProviders in TestNG

Create a class for the DataProvider method.

DataProvider Class:
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.

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.openqa.selenium.chrome.ChromeDriver;
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>();
     
     @BeforeMethod
    public void setUp(){
 
        System.setProperty("webdriver.chrome.driver",
                "C:\\Users\\Vibha\\Software\\chromedriver\\chromedriver.exe");
        driver = new ChromeDriver();
        WEBDRIVER_THREADLOCAL.set(driver);
        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();
        driver.manage().window().maximize();
        driver.get("https://opensource-demo.orangehrmlive.com/");
      
        Thread.sleep(2000);
        driver.findElement(By.name("txtUsername")).sendKeys(username);
        System.out.println("Username :" + username);
         
        Thread.sleep(2000);
        driver.findElement(By.name("txtPassword")).sendKeys(password);
        System.out.println("password :" + password);
         
        Thread.sleep(2000);
        String expectedError = driver.findElement(By.id("spanMessage")).getText();
        System.out.println("Error Message :" + expectedError);
        Assert.assertTrue(expectedError.contains(errorMessage));
 
    }
          
    @AfterMethod
    public void tear_down() {
          
         WebDriver driver = WEBDRIVER_THREADLOCAL.get();
         System.out.println("After method Thread Id:" + Thread.currentThread().getId());
            if (driver != null) {
                driver.quit();
         }
    }   
}

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

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