Detailed explanation

Junit is one of the most common unit test frameworks in Java. It provides the Junit Platform Runner to perform the test code.The technical principles of the Junit platform operator are as follows: 1. Comment driver: Junit platform operator uses the annotation driver to identify the test code.The test class and test methods need to add specific annotations, such as `@test` to tell Junit operators that they are test cases. 2. Reflective mechanism: Junit platform operator uses Java's reflection mechanism to detect and execute test code.It can dynamically load and instantiate the test class and call the test method through reflection. 3. Life cycle management: JUNIT platform operator management tests all stages of life cycle.It will perform some preparations before the test starts, such as creating test objects and setting the test environment.It then runs each test method in the predetermined order, and performs some cleaning work before and after the test method is executed. 4. Eclabo mechanism: Junit platform operator uses an assertion mechanism to verify the test results.The test code can be used to determine whether the expected results are consistent with the actual results.If the assertion fails, Junit will display error information in the test report. Below is a simple example code that shows how to use the Junit platform operator to perform the test code: import org.junit.jupiter.api.Assertions; import org.junit.jupiter.api.Test; import org.junit.platform.runner.JUnitPlatform; import org.junit.runner.RunWith; @RunWith(JUnitPlatform.class) public class MyTest { @Test void testAddition() { int result = 1 + 2; Assertions.assertEquals(3, result); } } In this example, `@Runwith` Note tell Junit to use the Junit platform operator to execute the test code.`@Test` Mark a test method` testadDition () `.This method uses an assertion `assertions.assertequals ()` to verify whether the result of 1 + 2 is equal to 3. The above is the technical principle of the Junit platform operator.By using the Junit platform operator, developers can easily write and perform unit test code to improve software quality and stability.