Different types of JUnit annotations and their use in writing unit tests

JUnit provides various annotations that can be used to define the behavior of unit tests. Here are some of the most commonly used annotations:

• @Test: This annotation is used to mark a method as a test method that should be run by JUnit. These methods can be parameterized with the optional attributes such as expected exceptions or timeouts.
• @Before: This annotation is used to mark a method that should run before each test method. It is typically used to set up any preconditions necessary for the test.
• @After: This annotation is used to mark a method that should run after each test method. It is typically used to clean up any resources used during the test.
• @BeforeClass: This annotation is used to mark a method that should run once before any of the test methods in the class. It is typically used for expensive setup operations.
• @AfterClass: This annotation is used to mark a method that should run once after all the test methods in the class have been executed. It is typically used for cleanup operations.

These annotations provide a way to control the execution flow of unit tests and ensure that the necessary setup and cleanup operations are performed before and after each test method. By using these annotations effectively, developers can write robust and reliable unit tests for their Java applications.