Testing Platform : JUnit 5

JUnit 5 is a platform, not a framework. It fixed the core architectural limitations of JUnit 4 by decoupling test execution from test definition.

JUnit 4 (Vintage) was a monolithic framework where everything was tightly coupled. JUnit 5, on the other hand, is built with a modular architecture:

• JUnit Platform for test discovery and execution
• Launcher as a single entry point for IDEs, Maven, and CI tools
• Test Engines for actual test execution

JUnit 5 tests run on the Jupiter Engine, while legacy JUnit 3/4 tests run via the Vintage Engine — all on the same platform.

This design makes JUnit 5:

• Backward compatible
• Tool-agnostic
• Extensible and future-proof