TestNG Interview Questions and Answers for 10 years experience

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100 TestNG Interview Questions & Answers (10 Years Experience)

  1. What is TestNG? How does it differ from JUnit?

    • Answer: TestNG is a testing framework inspired by JUnit and NUnit but introducing several new functionalities, such as annotations, powerful execution models, and a more extensive reporting mechanism. Key differences include TestNG's support for annotations like @DataProvider, @Factory, and @Listeners, its ability to run tests in parallel, and its more comprehensive HTML reports. JUnit is simpler and focuses primarily on unit testing, while TestNG offers a broader approach encompassing various testing styles (unit, integration, functional).

  2. Explain the different annotations used in TestNG.

    • Answer: TestNG uses numerous annotations to control test execution. Key annotations include: @Test (marks a test method), @BeforeSuite/@AfterSuite (run once before/after all tests), @BeforeTest/@AfterTest (run before/after each test), @BeforeClass/@AfterClass (run once before/after all methods in a class), @BeforeMethod/@AfterMethod (run before/after each test method), @DataProvider (provides data for test methods), @Factory (creates multiple test instances), @Parameters (receives parameters from testng.xml), @Listeners (adds listeners for custom reporting or actions).

  3. How do you handle exceptions in TestNG?

    • Answer: TestNG allows handling exceptions using the `expectedExceptions` attribute within the `@Test` annotation. You specify the expected exception class, and the test passes if the specified exception is thrown. Alternatively, you can use try-catch blocks within your test methods to handle exceptions gracefully and log relevant information for debugging.

  4. Explain the concept of Data Providers in TestNG.

    • Answer: Data Providers are methods annotated with `@DataProvider` that return data sets to be used by test methods. This enables parameterized testing, where the same test method is executed multiple times with different input data, enhancing test coverage and efficiency. Data can be provided in various formats, such as Object arrays, two-dimensional arrays, or Iterators.

  5. How to run TestNG tests in parallel?

    • Answer: TestNG supports parallel test execution using the `parallel` attribute in the `testng.xml` file. Values include "methods" (runs tests from different methods in parallel), "tests" (runs different tests in parallel), and "classes" (runs tests from different classes in parallel). The `thread-count` attribute specifies the number of threads to use.

  6. What are TestNG Listeners? Give examples.

    • Answer: TestNG Listeners are classes that implement specific interfaces (like `IReporter`, `ITestListener`, `ISuiteListener`) to extend TestNG's functionality. They allow customization of reporting, test execution flow, and other aspects. Examples include creating custom reports, modifying test results, logging events, and taking screenshots on test failures.

  7. How to generate reports in TestNG?

    • Answer: TestNG automatically generates an HTML report after test execution. You can customize the report using Listeners or external reporting tools. Listeners can generate custom reports in various formats (e.g., Extent Reports, Allure) providing more detailed information or visualizations.

  8. Explain the concept of TestNG Suites.

    • Answer: TestNG Suites are XML files (`testng.xml`) that define which tests, classes, or groups of tests should be executed. They provide a mechanism to organize and run multiple tests together, enabling more structured test execution and the ability to run specific subsets of tests.

  9. How to skip tests in TestNG?

    • Answer: Tests can be skipped using the `enabled` attribute within the `@Test` annotation (setting it to `false`). Alternatively, you can use `@Test(dependsOnMethods = {"method1"})` to make a test depend on another. If the depended-upon method fails, the dependent test is skipped. You can also programmatically skip tests within the test method itself using `throw new SkipException("Reason for skipping")`.

  10. What is the difference between @BeforeTest and @BeforeClass?

    • Answer: `@BeforeTest` runs before each test in a TestNG test suite, regardless of the number of classes or methods. `@BeforeClass` runs only once before any test method within a single class is executed. The execution order between these two would be `@BeforeTest`, then `@BeforeClass`, followed by the test methods, and concluding with `@AfterClass` and `@AfterTest`.

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