What is the difference between TestNG and JUnit?

Both TestNG and JUnit are popular testing frameworks for Java, but TestNG offers more advanced features for test automation.

Key Differences

Annotations:

• TestNG: @BeforeSuite, @AfterSuite, @BeforeTest, @AfterTest, @BeforeClass, @AfterClass, @BeforeMethod, @AfterMethod
• JUnit: @BeforeAll, @AfterAll, @BeforeEach, @AfterEach (fewer options)

Test Dependencies:

• TestNG: Supports test dependencies using dependsOnMethods
• JUnit: No built-in support for dependencies

Parallel Execution:

• TestNG: Built-in support for parallel execution
• JUnit: Limited parallel execution support

Parameterization:

• TestNG: @DataProvider for complex parameterization
• JUnit: @ParameterizedTest (simpler)

Grouping:

• TestNG: Can group tests and run specific groups
• JUnit: Uses @Tag (less flexible)

Reporting:

• TestNG: Built-in HTML reports
• JUnit: Requires external tools for detailed reports

TestNG Example

@Test(priority = 1, groups = {"smoke"})
public void loginTest() {
    // Test code
}

@Test(priority = 2, dependsOnMethods = {"loginTest"})
public void dashboardTest() {
    // Test code
}

@DataProvider(name = "testData")
public Object[][] getData() {
    return new Object[][] {{"user1", "pass1"}, {"user2", "pass2"}};
}

@Test(dataProvider = "testData")
public void loginWithData(String username, String password) {
    // Test with different data
}

When to Use

• TestNG: Complex test suites, parallel execution, data-driven testing, Selenium automation
• JUnit: Simple unit tests, Spring Boot applications, basic testing needs