TestNG
TestNG is a testing framework for Java, inspired by JUnit but adding features like flexible test configuration, parallel execution, data providers, and grouping — designed originally to address gaps in older JUnit versions, and widely used for both unit testing and larger automation suites.
TestNG's annotation-based structure will look familiar to JUnit users, but it adds capabilities that matter more for larger automation suites than pure unit testing: built-in parallel test execution, dependency ordering between tests, flexible grouping (run just the "smoke" group, or just "regression"), and data providers for parameterized, data-driven tests.
It's especially common as the runner underneath Selenium-based automation suites in Java, where its grouping and parallelization features map naturally onto the need to run different subsets of a large UI test suite — smoke, regression, cross-browser — under different conditions.
