The following example provides JUnit Jupiter Minimum requirements for writing tests in .

package com.example.util;public class Calculator {    public int add(int number1, int number2) {        return number1 + number2;    }}

package com.example;import com.example.util.Calculator;import org.junit.jupiter.api.Test;import static org.junit.jupiter.api.Assertions.*;public class MyFirstJUnitJupiterTests {    private final Calculator calculator = new Calculator();    @Test    void addition() {        assertEquals(2, calculator.add(1, 1));    }}

1. Annotation Overview

JUnit Jupiter Support the following annotations for configuring the testing and extension framework . Unless otherwise stated , All core annotations are located in org.junit.jupiter.api In bag , This bag is in junit-jupiter-api Module .

2. Meta annotation and composite annotation

JUnit Jupiter Annotations can be used as meta annotations . It means that you can define your own combination annotation , The annotation will automatically inherit the semantics of its meta annotation .
such as , You can create a named @Tag(“fast”) Custom combination annotation , Instead of copying and pasting from the entire code base @Tag(“fast”), As shown below . then @Fast Can be used as @Tag(“fast”) A direct alternative to .

import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;import org.junit.jupiter.api.Tag;@Target({ElementType.TYPE, ElementType.METHOD})@Retention(RetentionPolicy.RUNTIME)@Tag("fast")public @interface Fast {}

The following @Test The method describes @Fast Use of annotations

@Fast@Testvoid myFastTest(){    //...}

3. Test classes and methods

Test class ： Any top-level class that contains at least one test method 、 Static member class or @Nested class . Test classes cannot be abstract , And must have a single constructor .
The test method ： Use @Test、@RepeatedTest、@ParameerizedTest、@TestFactory or @TestTemplate Any instance method of direct annotation or meta annotation .
Life cycle approach ： Use @BeforeAll、@AfterAll、@BeforeEach or @AfterEach Any method of direct annotation or meta annotation .
Test methods and lifecycle methods can be declared locally in the current test class , Inherit from superclass , You can also inherit from the interface （ Refer to test interfaces and default methods ）. Besides , Test methods and life cycle methods should not be abstract , And must not return a value （ Return the required value @TestFactory Methods except ）.
Visibility of classes and methods ： Test class 、 Test methods and life cycle methods do not require public, But not for private. It is generally recommended to omit the test class 、 Of test methods and life cycle methods public Modifier , Unless there are technical reasons to do so . for example , When a test class is extended by a test class in another package . Classes and methods plus public Another technical reason is , In the use of Java Module system , Simplify testing on the module path .
The following test class demonstrates the use of @Test Methods and all supported lifecycle methods . More information on testing execution order and callback wrapping behavior .
Example ： Set to fail the test

import org.junit.jupiter.api.*;import static org.junit.jupiter.api.Assertions.*;import static org.junit.jupiter.api.Assumptions.*;class StandardTests {    @BeforeAll    static void initAll() {    }    @BeforeEach    void init() {    }    @Test    void succeedingTest() {    }    @Test    void failingTest() {        fail("a failing test");    }    @Test    @Disabled("for demonstration purposes")    void skippedTest(){        //not executed    }    @Test    void abortedTest() {        assumeTrue("abc".contains("Z"));        fail("test should have been aborted");    }    @AfterEach    void tearDown() {    }    @AfterAll    static void tearDownAll() {    }}

Output results

Example ： Set to pass the test

import org.junit.jupiter.api.*;import static org.junit.jupiter.api.Assertions.*;import static org.junit.jupiter.api.Assumptions.*;class StandardTests {    @BeforeAll    static void initAll() {    }    @BeforeEach    void init() {    }    @Test    void succeedingTest() {    }    @Test    void failingTest() {        //fail("a failing test");    }    @Test    @Disabled("for demonstration purposes")    void skippedTest(){        //not executed    }    @Test    void abortedTest() {        assumeTrue("abc".contains("c"));        //fail("test should have been aborted");    }    @AfterEach    void tearDown() {    }    @AfterAll    static void tearDownAll() {    }}

Output results