How do you integrate Selenium with TestNG or JUnit?

The runner owns discovery, ordering, parallelism and reporting. Selenium only drives the browser. A base class or extension is the natural place for driver creation, navigation, screenshots on failure and cleanup.

public abstract class BaseTest {
    protected WebDriver driver;

    @BeforeMethod
    public void setUp() {
        driver = DriverFactory.create();
    }

    @AfterMethod(alwaysRun = true)
    public void tearDown() {
        if (driver != null) {
            driver.quit();
        }
    }
}

public class LoginTest extends BaseTest {
    @Test
    public void userCanSignIn() {
        new LoginPage(driver).signIn("asha@example.com", "correct-horse");
        Assert.assertTrue(driver.getCurrentUrl().contains("/dashboard"));
    }
}

• TestNG uses @BeforeMethod and @AfterMethod; JUnit 5 uses @BeforeEach and @AfterEach
• alwaysRun or equivalent ensures cleanup runs after a failure
• Screenshots on failure belong in a listener, not in every test
• Parallel configuration belongs in the runner configuration, not in test code
• Keep test data creation explicit so failures are reproducible

A common mistake is a static shared driver. It makes tests interfere through cookies, navigation and window state, and it breaks as soon as parallelism is enabled. One driver per test method is the simplest safe default; use a suite-level driver only for a deliberate, isolated smoke flow.