What is TestNG?

TestNG (Next Generation) is a powerful testing framework for Java, inspired by JUnit and NUnit. It is designed to cover all categories of tests — unit, functional, end-to-end, and integration tests — and integrates seamlessly with Selenium.

Key capabilities:

• ✓Assertions – Validate expected vs actual results (Assert.assertEquals, Assert.assertTrue)
• ✓Reporting – Generates HTML and XML test reports automatically
• ✓Parallel Execution – Run tests simultaneously across threads or browsers
• ✓Data-Driven Testing – @DataProvider feeds multiple data sets into one test
• ✓Grouping – Tag tests into groups (sanity, regression) and selectively run them
• ✓Dependency – Control execution order with dependsOnMethods
• ✓Parameterization – Pass external values via testng.xml using @Parameters

Minimal example:

import org.testng.annotations.Test;
import org.testng.Assert;

public class LoginTest {
    @Test
    public void verifyLogin() {
        String actual = "Welcome";
        Assert.assertEquals(actual, "Welcome", "Login failed!");
    }
}

Why TestNG over JUnit?

TestNG is the most popular choice for Selenium automation projects in Java.