Explore the technical principles of the Junit Jupiter Engine framework in the Java library

Junit Jupiter Engine is a framework in the Java class library, which is used to perform and manage Junit 5 test cases.The in -depth understanding of Junit Jupiter Engine's technical principles is essential for developers.This article will explore the technical principles of the Junit Jupiter Engine framework and help readers better understand through some Java code examples. Junit Jupiter Engine is a core component of Junit 5, which is responsible for analysis and execution of test cases.It creates the data model of the test case through the description, status, and results of the use case, and creates the corresponding test example examples through reflection technology.Junit Jupiter Engine uses annotations to mark the test method, and is executed by the engine cycle management test case. The core principle of Junit Jupiter Engine is based on three key concepts: test engines, test descriptions, and test actuators. First of all, the test engine is the core component of Junit Jupiter Engine. It is responsible for initializing test cases and coordinating the entire test process.The test engine is responsible for loading test cases, discovering test descriptions and processing test results.Junit Jupiter Engine provides a default test engine, which also allows developers to customize test engines to meet specific needs. Secondly, the test description is metadata used to describe the test case.Test descriptions usually use @Test annotations for labeling, which indicates that the method is a test method.Test descriptions can also use other annotations to specify the testing conditions, rear operations and expectations of the test. Finally, the test actuator is a component responsible for the actual execution of the test case.Testing the actuator to create an instance of test cases by reflecting technology and call the test method for testing.Testing the actuator is also responsible for managing the life cycle of test cases, including initialization, execution, and cleaning.Junit Jupiter Engine provides the default test actuators, and also supports custom operators to meet different needs. The following is a simple sample code, which demonstrates how to use the Junit Jupiter Engine framework to write and execute test cases: import org.junit.jupiter.api.Assertions; import org.junit.jupiter.api.Test; public class CalculatorTest { @Test void testAddition() { Calculator calculator = new Calculator(); int result = calculator.add(2, 3); Assertions.assertEquals(5, result); } } In the above example, we created a test class called the `CalculatorTest`, and defined a test method` testadition`.This method uses the `@test` annotation provided by Junit Jupiter Engine to indicate that it is a test method.In the test method, we created a `Calculator" object and call its `add` method for additional calculation.Finally, we use the method of `Assertions.assertequals` to assert that the calculation results are equal to the expected results. Through the above examples, we can see that Junit Jupiter Engine simplifies the writing and execution process of test cases by introducing annotations and testing actuators.It provides flexible test descriptions and scalable test engines, allowing developers to easily write, execute and manage test cases to improve code quality and software reliability. To sum up, Junit Jupiter Engine is an important framework in the Java class library to perform and manage Junit 5 test cases.This article explores Junit Jupiter Engine from the perspective of technical principles, and demonstrates how to use the framework to write and execute test cases through a simple example code.The technical principles of mastering Junit Jupiter Engine are very important for developers. It can help developers better test code and improve software quality.