JUnit5 快速指南

JUnit5 快速指南

version: junit5

• 1. 安装
• 2. JUnit 注解
• 3. 编写单元测试
  • 3.1. 基本的单元测试类和方法
  • 3.2. 定制测试类和方法的显示名称
  • 3.3. 断言（Assertions）
  • 3.4. 假想（Assumptions）
  • 3.5. 禁用
  • 3.6. 测试条件
  • 3.7. 嵌套测试
  • 3.8. 重复测试
  • 3.9. 参数化测试
• 4. 引用和引申

1. 安装

在 pom 中添加依赖

<properties>
  <junit.jupiter.version>5.3.2</junit.jupiter.version>
</properties>

<dependencies>
  <dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter-api</artifactId>
    <version>${junit.jupiter.version}</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter-params</artifactId>
    <version>${junit.jupiter.version}</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter-engine</artifactId>
    <version>${junit.jupiter.version}</version>
    <scope>test</scope>
  </dependency>
</dependencies>

组件间依赖关系：

2. JUnit 注解

Annotation	Description
@Test	Denotes that a method is a test method. Unlike JUnit 4’s @Test annotation, this annotation does not declare any attributes, since test extensions in JUnit Jupiter operate based on their own dedicated annotations. Such methods are inherited unless they are overridden.
@ParameterizedTest	Denotes that a method is a parameterized test. Such methods are inherited unless they are overridden.
@RepeatedTest	Denotes that a method is a test template for a repeated test. Such methods are inherited unless they are overridden.
@TestFactory	Denotes that a method is a test factory for dynamic tests. Such methods are inherited unless they are overridden.
@TestInstance	Used to configure the test instance lifecycle for the annotated test class. Such annotations are inherited.
@TestTemplate	Denotes that a method is a template for test cases designed to be invoked multiple times depending on the number of invocation contexts returned by the registered providers. Such methods are inherited unless they are overridden.
@DisplayName	Declares a custom display name for the test class or test method. Such annotations are not inherited.
@BeforeEach	Denotes that the annotated method should be executed before each @Test, @RepeatedTest, @ParameterizedTest, or @TestFactory method in the current class; analogous to JUnit 4’s @Before. Such methods are inherited unless they are overridden.
@AfterEach	Denotes that the annotated method should be executed after each @Test, @RepeatedTest, @ParameterizedTest, or @TestFactory method in the current class; analogous to JUnit 4’s @After. Such methods are inherited unless they are overridden.
@BeforeAll	Denotes that the annotated method should be executed before all @Test, @RepeatedTest, @ParameterizedTest, and @TestFactory methods in the current class; analogous to JUnit 4’s @BeforeClass. Such methods are inherited (unless they are hidden or overridden) and must be static (unless the "per-class" test instance lifecycle is used).
@AfterAll	Denotes that the annotated method should be executed after all @Test, @RepeatedTest, @ParameterizedTest, and @TestFactory methods in the current class; analogous to JUnit 4’s @AfterClass. Such methods are inherited (unless they are hidden or overridden) and must be static (unless the "per-class" test instance lifecycle is used).
@Nested	Denotes that the annotated class is a nested, non-static test class. @BeforeAll and @AfterAllmethods cannot be used directly in a @Nested test class unless the "per-class" test instance lifecycle is used. Such annotations are not inherited.
@Tag	Used to declare tags for filtering tests, either at the class or method level; analogous to test groups in TestNG or Categories in JUnit 4. Such annotations are inherited at the class level but not at the method level.
@Disabled	Used to disable a test class or test method; analogous to JUnit 4’s @Ignore. Such annotations are not inherited.
@ExtendWith	Used to register custom extensions. Such annotations are inherited.

3. 编写单元测试

3.1. 基本的单元测试类和方法

import org.junit.jupiter.api.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

class Junit5StandardTests {

    private static final Logger LOGGER = LoggerFactory.getLogger(Junit5StandardTests.class);

    @BeforeAll
    static void beforeAll() {
        LOGGER.info("call beforeAll()");
    }

    @BeforeEach
    void beforeEach() {
        LOGGER.info("call beforeEach()");
    }

    @Test
    void succeedingTest() {
        LOGGER.info("call succeedingTest()");
    }

    @Test
    void failingTest() {
        LOGGER.info("call failingTest()");
        // fail("a failing test");
    }

    @Test
    @Disabled("for demonstration purposes")
    void skippedTest() {
        LOGGER.info("call skippedTest()");
        // not executed
    }

    @AfterEach
    void afterEach() {
        LOGGER.info("call afterEach()");
    }

    @AfterAll
    static void afterAll() {
        LOGGER.info("call afterAll()");
    }
}

3.2. 定制测试类和方法的显示名称

支持普通字符、特殊符号、emoji

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

@DisplayName("A special test case")
class JunitDisplayNameDemo {

    @Test
    @DisplayName("Custom test name containing spaces")
    void testWithDisplayNameContainingSpaces() { }

    @Test
    @DisplayName("╯°□°）╯")
    void testWithDisplayNameContainingSpecialCharacters() { }

    @Test
    @DisplayName("