TestNG Interview Questions & Answers (1970)

TestNG is a Java testing framework inspired by JUnit but designed for a wider range of test categories — unit, integration, end-to-end, and functional. It's the default runner for enterprise Selenium suites in 2026.

<dependency>
  <groupId>org.testng</groupId>
  <artifactId>testng</artifactId>
  <version>7.10.2</version>
  <scope>test</scope>
</dependency>

The suite configuration file. Defines which classes/methods run, in which order, parallel mode, groups, and parameters.

<suite name="Regression" parallel="tests" thread-count="4">
  <test name="Chrome">
    <parameter name="browser" value="chrome"/>
    <classes><class name="tests.LoginTest"/></classes>
  </test>
</suite>

mvn test -Dtest=LoginTest#validLogin
# or from testng.xml, use <methods><include name="validLogin"/></methods>

• @Test, @BeforeSuite/@AfterSuite
• @BeforeTest/@AfterTest
• @BeforeClass/@AfterClass
• @BeforeMethod/@AfterMethod
• @DataProvider, @Parameters, @Listeners, @Factory

@BeforeSuite → @BeforeTest → @BeforeClass → @BeforeMethod → @Test → @AfterMethod → @AfterClass → @AfterTest → @AfterSuite.

@BeforeTest runs once per <test> block in the XML. @BeforeMethod runs before every single @Test method — used for per-test setup like opening a browser.

@Test
public void featureFlagged() {
  if (!Config.isEnabled("beta")) throw new SkipException("Beta off");
  // ...
}

SoftAssert soft = new SoftAssert();
soft.assertEquals(title, "Home");
soft.assertTrue(banner.isDisplayed());
soft.assertAll(); // required, else failures are swallowed

Soft assertions collect failures and report all of them at the end.

@Test(priority = 1, groups = {"smoke"}, timeOut = 5000,
      dependsOnMethods = "login", enabled = true,
      description = "Add to cart")
public void addToCart() { /* ... */ }

@Test(groups = {"smoke", "regression"})
public void t1() {}

<groups><run><include name="smoke"/></run></groups>

@Test(priority = N) — lower N runs first. Ties are alphabetical. Don't rely on priority for real dependencies; use dependsOnMethods.

Ensures a prerequisite test passes before dependents run. If the parent fails, dependents are marked SKIPPED, not failed.

public class Retry implements IRetryAnalyzer {
  int count = 0, max = 2;
  public boolean retry(ITestResult r) { return count++ < max; }
}
@Test(retryAnalyzer = Retry.class) public void flaky() {}

To programmatically apply annotations at load time — e.g. attach a Retry analyzer to every @Test without editing each class.

Per test: @Test(timeOut = 5000). Suite-wide: <suite time-out="5000"> in testng.xml.

@Test(expectedExceptions = IllegalArgumentException.class,
       expectedExceptionsMessageRegExp = "id.*required")
public void invalidInput() { service.create(null); }

@DataProvider(name = "logins")
public Object[][] logins() {
  return new Object[][]{ {"a@x.com","p1"}, {"b@x.com","p2"} };
}
@Test(dataProvider = "logins")
public void login(String email, String pwd) { /* ... */ }

Read the file inside the @DataProvider and return Object[][]. Popular libs: Apache POI (Excel), OpenCSV (CSV), Jackson (JSON).

@Parameters reads static values from testng.xml (like browser name). @DataProvider supplies dynamic in-code datasets and drives multiple iterations of one test.

<parameter name="browser" value="chrome"/>

@Test @Parameters("browser")
public void open(String browser) { /* ... */ }

<suite name="R" parallel="methods" thread-count="8">

Values: tests, classes, methods, instances. Combine with a ThreadLocal<WebDriver> to keep browser instances isolated.

An interface that hooks into TestNG events. Implement ITestListener to add screenshots on failure, Extent Report entries, or Slack notifications.

@Listeners(ScreenshotListener.class)
public class BaseTest {}

Creates test class instances at runtime — useful when the same tests need to run for many test-data rows or configurations.

Extend a BaseTest that has @BeforeMethod to launch the browser and @AfterMethod to quit it. Page objects are instantiated inside tests. See our POM guide (concepts translate to Java).

Default: test-output/emailable-report.html. Popular add-ons: ExtentReports, Allure, ReportPortal. Wire them via a Listener.

- run: mvn -B test -DsuiteXmlFile=testng.xml
- uses: actions/upload-artifact@v4
  if: always()
  with: { name: reports, path: test-output/ }