TestNG is a next generation testing framework of JUnit and NUnit which have enhanced functionalities for making it more useful:
1. It has Flexible test configuration.
2. It has support for data-driven testing
3. It has support for parameters.
4. It allows distribution of tests on slave machines.
5. Powerful execution model (no more TestSuite).
6. It is Supported by a variety of tools and plug-ins
7. Dependent methods for application server testing.
Due to its advantages, the automation testing company extensively uses TestNG for Selenium automation and code testing instead of JUnit. For automation testing company , TestNG Selenium automation becomes simplified and the parallel execution using Selenium Grid becomes easy. Also, TestNG have a lot of features in it.
Advantages of TestNG over Junit:
1. In TestNG there is no constraint like you have to declare @BeforeClass and @AfterClass, which is present in JUnit.
2. Additional Levels of setUp/tearDown level are available in TestNG like @Before/AfterSuite,@Before/AfterTest and @Before/AfterGroup
3. TestNG provides different type of Annotations which are easy to understand over JUnit.
4. TestNG allows you grouping of test cases easily which is not possible in JUnit.
5. In TestNg you can give any name to the test methods.
6. TestNG allows us to define the dependent test cases each test case is independent to other test case.
7. TestNG allows us to execute of test cases based on group. Let’s take a scenario where we have created two set of groups “Regression” & “Sanity”. If we want to execute the test cases under Sanity group then it is possible in TestNG framework.
8. Parallel execution of Selenium test cases is possible in TestNG.