Junit 5 Architecture

Junit 5 Architecture has three main components -

• Junit Platform

  It provides a core foundation to help launching testing frameworks on JVM. It acts as an interface between JUnit and its clients such as build tools (`Maven and Gradle`) and IDE's (`Eclipse and IntelliJ`). It introduces the concept of a `Launcher` which external tools use to discover, filter, and execute tests.
  

It also provides the TestEngine API for developing a testing framework that runs on the JUnit platform. Using TestEngine API, 3rd party testing libraries such as Spock, Cucumber, and FitNesse can directly plug in and provide their custom TestEngine.

• Junit Jupiter

  It provides a new programming model and extension model for writing tests and extensions in Junit 5. It has a whole new annotation to write test cases in Junit 5. Some of the annotations are `@BeforeEach`, `@AfterEach`, `@AfterAll`, `@BeforeAll` etc. It implements TestEngine API provided by Junit Platform so that Junit 5 test can be run.

• Junit Vintage

  The term `Vintage` basically means **classic**. Thus, this sub-project provides extensive support for writing test cases in JUnit 4 and JUnit 3. Thus, backward compatibility is been provided by this project.

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In the next lesson, we will learn to create our first JUnit 5 test case.