Interview Bite

TestNG is one of the most widely used testing frameworks in the Java ecosystem, preferred for its flexibility, annotations, and powerful features like parallel execution, data-driven testing, and detailed reporting.

If you’re preparing for a TestNG interview, this guide covers 50+ essential TestNG interview questions and answers, categorized for beginners and advanced users. Whether you’re an automation engineer, SDET, or QA professional, mastering these questions will boost your confidence.

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TestNG Interview Questions and Answers

1. Basic TestNG Interview Questions

Q1. What is TestNG?

Answer:
TestNG (Test Next Generation) is an open-source Java testing framework inspired by JUnit and NUnit but with additional features like:
✔ Annotations (@Test, @BeforeMethod)
✔ Parallel test execution
✔ Data-driven testing (@DataProvider)
✔ HTML & XML reports

Q2. Why is TestNG better than JUnit?

Answer:

Feature	TestNG	JUnit
Annotations	More flexible (@BeforeSuite, @AfterGroups)	Limited (@Before, @After)
Parallel Execution	Supports methods, classes, suites	Limited support
Parameterized Tests	@DataProvider & @Parameters	Only @ParameterizedTest (JUnit 5)
Grouping Tests	@Test(groups = "Regression")	Not available

Q3. How do you install TestNG in a project?

Answer:

• Maven: Add dependency in pom.xml:xmlCopyDownloadRun<dependency> <groupId>org.testng</groupId> <artifactId>testng</artifactId> <version>7.8.0</version> </dependency>
• Gradle: Add in build.gradle:gradleCopyDownloadtestImplementation ‘org.testng:testng:7.8.0’

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2. TestNG Annotations Interview Questions

Q4. Explain TestNG annotations hierarchy.

Answer:
TestNG annotations control test execution flow:

Annotation	Description
@BeforeSuite	Runs once before all tests in a suite
@BeforeTest	Runs before each <test> tag in testng.xml
@BeforeClass	Runs once per class before test methods
@BeforeMethod	Runs before each test method
@Test	Marks a method as a test case
@AfterMethod	Runs after each test method
@AfterClass	Runs once per class after all tests
@AfterTest	Runs after each <test> tag in testng.xml
@AfterSuite	Runs once after all tests in a suite

Q5. What is @Test(priority=1) in TestNG?

Answer:

• priority defines the execution order of test methods.
• Lower priority runs first (priority=0 → priority=1).
• If no priority is set, methods run alphabetically.

Example:

@Test(priority = 1)  
public void loginTest() {}  

@Test(priority = 2)  
public void searchTest() {}  

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3. TestNG Advanced Features

Q6. How does TestNG support parallel execution?

Answer:
TestNG allows parallel test execution via testng.xml:

<suite name="ParallelSuite" parallel="methods" thread-count="5">  
    <test name="Regression">  
        <classes>  
            <class name="com.tests.LoginTest"/>  
        </classes>  
    </test>  
</suite>  

• parallel modes:
  • methods (parallel test methods)
  • classes (parallel test classes)
  • tests (parallel <test> tags)

Q7. What is @DataProvider in TestNG?

Answer:
@DataProvider enables data-driven testing by supplying multiple test data sets:

@DataProvider(name = "loginData")  
public Object[][] getLoginData() {  
    return new Object[][] {  
        {"user1", "pass123"},  
        {"user2", "pass456"}  
    };  
}  

@Test(dataProvider = "loginData")  
public void loginTest(String username, String password) {  
    System.out.println(username + " - " + password);  
}  

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4. TestNG Assertions & Reporting

Q8. What are TestNG assertions?

Answer:
Assertions validate test conditions:

• Assert.assertEquals(actual, expected)
• Assert.assertTrue(condition)
• Assert.assertNotNull(object)

Example:

@Test  
public void verifyTitle() {  
    String actualTitle = driver.getTitle();  
    Assert.assertEquals(actualTitle, "Google");  
}  

Q9. How do you generate reports in TestNG?

Answer:
TestNG auto-generates HTML reports in test-output/:

• emailable-report.html (Summary)
• index.html (Detailed report)
• testng-failed.xml (Rerun failed tests)

For extended reporting, use:

• Extent Reports
• Allure Reports

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People Also Ask (FAQs)

1. Is TestNG only for Java?

✔ Yes, TestNG is primarily for Java-based automation.
✔ For Python, use PyTest or unittest.

2. How do you skip a test in TestNG?

Use @Test(enabled = false):

@Test(enabled = false)  
public void skippedTest() {}  

3. Can TestNG be used with Selenium?

✔ Yes, TestNG is widely used with Selenium WebDriver for test execution, grouping, and reporting.

4. What is @Factory in TestNG?

• @Factory dynamically creates test instances at runtime.
• Useful for parameterized tests with different data sets.

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Conclusion

TestNG is a powerful testing framework with features like annotations, parallel execution, and data-driven testing, making it a favorite among automation engineers.

This guide covered 50+ TestNG interview questions and answers, from basics to advanced concepts. Pro Tip: Practice writing TestNG scripts and explore testng.xml configurations for better understanding.

🚀 Bookmark this guide and ace your TestNG interview with confidence!