What is TestNG Annotations?
In TestNG (a Java testing framework), an annotation is a form of metadata—marked by the @ symbol—that you place on classes or methods to tell TestNG how and when to execute them. Instead of hard-coding the test logic or relying on naming conventions, you use annotations to:
- Define test methods (e.g. @Test)
- Specify setup and teardown routines at various scopes (suite, test, class, method)
- Drive data-driven tests (@DataProvider, @Parameters)
- Control execution order and dependencies (dependsOnMethods, alwaysRun, etc.)
- Group tests and apply group-specific configuration (@BeforeGroups, @AfterGroups)
Under the hood, TestNG reads these annotations via Java’s reflection API at runtime. When it sees, for example, @BeforeMethod on a method, it will automatically invoke that method before each @Test in the same class. This declarative approach makes your test code clean, flexible, and easy to configure without boilerplate.
Use of Annotations:
1. Test Definition
@Test
Marks a method as a test case.
Explanation: TestNG will run any method annotated with @Test. You can further control invocation (e.g., priority, groups, dependsOnMethods, enabled) via its attributes.
2. Configuration (Global)
@BeforeSuite
Runs once before all tests in the entire suite.
Explanation: Ideal for suite-wide setup tasks (e.g., loading global configuration).
@AfterSuite
Runs once after all tests in the entire suite.
Explanation: Ideal for suite-wide teardown (e.g., generating consolidated reports).
3. Configuration (Test Tag in XML)
@BeforeTest
Runs before any <test> tag in the TestNG XML.
Explanation: Use when you have multiple <test> sections and need setup per section.
@AfterTest
Runs after all methods in a <test> tag have run.
Explanation: Corresponds to cleanup per <test> section.
4. Configuration (Class Level)
@BeforeClass
Runs once before the first method in the current class is invoked.
Explanation: Class-level initialization (e.g., instantiate class-scoped resources).
@AfterClass
Runs once after all methods in the current class have run.
Explanation: Class-level cleanup (e.g., close resources opened in @BeforeClass).
5. Configuration (Method Level)
@BeforeMethod
Runs before each test method.
Explanation: Prepares prerequisites needed for every individual test method.
@AfterMethod
Runs after each test method.
Explanation: Cleans up after each test, ensuring isolation between tests.
6. Group Configuration
@BeforeGroups
Runs before the first test method that belongs to any of the specified groups.
Explanation: Use when you want setup to run once per group of tests.
@AfterGroups
Runs after all test methods in the specified groups have run.
Explanation: Performs group-specific teardown.
7. Parameterization & Data-Driven Testing
@DataProvider
Marks a method as supplying data for a test method.
Explanation: Returns an array of parameter sets; tests annotated with @Test(dataProvider=”…”) will run once per set.
@Parameters
Injects parameters from your TestNG XML into test methods or configuration methods.
Explanation: Useful for passing values (e.g., browser type, URLs) without hard-coding.
@Factory
Marks a method as a factory that returns objects containing test methods.
Explanation: Dynamically generates instances of test classes (and thus tests) at runtime.
8. Dependency & Sequencing
dependsOnMethods (attribute of @Test)
Specifies that this test method depends on one or more other methods.
Explanation: Ensures that if a prerequisite method fails/skips, dependent methods are skipped.
dependsOnGroups (attribute of @Test)
Declares dependency on a whole group of test methods.
Explanation: Skips tests until all methods in the named groups have passed.
9. Conditional Skipping
enabled (attribute of @Test)
Boolean flag to enable or disable a test method.
Explanation: Quickly include/exclude tests without removing the annotation.
alwaysRun (attribute of configuration annotations)
Forces a configuration method to run even if dependencies have failed or been skipped.
Explanation: Useful for cleanup that must occur regardless of earlier failures.
10. Miscellaneous
@Listeners
Associates listener classes (implementations of ITestListener, ISuiteListener, etc.) with your test class.
Explanation: Enables custom reporting, logging, or other behavior hooks.
@Optional
Used in conjunction with @Parameters to specify a default value when the parameter is not found in XML.
Explanation: Prevents runtime errors if an expected parameter is missing.
