Spring Boot Test单元测试——Junit4、Junit5区别与@ExtendWith不识别生效问题解析

小咪咪 2023-09-30 20:33 1阅读 0赞

## 一、SpringBoot2.4.x之后，改为默认仅集成JUnit5，干掉了兼容JUnit4 ##

#### 1. 根本原因 ####

> 新版本2.4之后的`spring-boot-starter-test中`去掉了兼容junit4引擎`org.junit.vintage:junit-vintage-engine`。

#### 2. SpringBoot2.4.0之后 ####

`spring-boot-starter-test`默认仅支持JUnit5

@ExtendWith(SpringExtension.class) // 注意这里
    @SpringBootTest
    public class Test{
        
     ...
    }

#### 3. SpringBoot2.4.0之前 ####

`spring-boot-starter-test`默认使用JUnit5，同时兼容支持JUnit4

@RunWith(SpringRunner.class) // 注意这里
    @SpringBootTest
    public class Test{
        
     ...
    }

#### 4. 特殊说明： ####

> **`spring-boot-starter-test版本`大于2.2小于2.4时，\**若想只用Junit5\**，需要\**excluding\** `org.junit.vintage:junit-vintage-engine，以刨除Junit4的干扰。`**

以下是引用stackoverflow中网友回答的原文（[java - spring-boot-starter-test with JUnit 5 - Stack Overflow][]）：

> A few additional notes to the ones mentioned by other contributors:
> 
> ### Using Spring Boot > 2.4.0 ###
> 
> If you are using Spring Boot > `2.4.0`, then there is nothing you have to do to use JUnit 5 Jupiter, because the `spring-boot-starter-test` library ***\*no longer includes the vintage-engine\**** dependency (which transitively included JUnit 4), just include the starter dependency to the project and you’re good to go. Use the `useJUnitPlatform()` in the Gradle configuration.
> 
> ### Using 2.4.0 > Spring Boot > 2.2.0 ###
> 
> If you use earlier versions, I’d suggest using a version higher than `2.2.0.RELEASE`, which is where the Spring team added support for JUnit 5 Jupiter into the `spring-boot-starter-test` ***\*by default\****.  
> In these versions, the library included the Vintage Engine dependency too, which could be used to run JUnit 4 tests using the JUnit 5 Jupiter platform. If you don’t need to execute JUnit 4 tests, then the spring team suggests excluding `org.junit.vintage:junit-vintage-engine` (not just `junit` as indicated in the description):
> 
>     testCompile('org.springframework.boot:spring-boot-starter-test') {
>          
>        exclude group: 'org.junit.vintage'
>     }
> 
> Here you would also need to configure the `useJUnitPlatform()` directive, of course.

##  ##

## 二、Junit5的@ExtendWith不识别生效问题 ##

#### 1. 在不同的Spring Boot版本中@ExtendWith的使用也有所不同 ####

其中在Spring boot 2.1.x之前：

> @SpringBootTest \*\**\*需要配合\**@ExtendWith(SpringExtension.class)\*\*才能正常工作的。

而在Spring boot **2.1.x之后：**

> 我们查看@SpringBootTest 的代码会发现，**其中已经组合了@ExtendWith(SpringExtension.class)**，因此，**无需**在进行该注解的使用了，进一步简化。

2.1之后的@SpringBootTest源码如下：

@Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Inherited
    @BootstrapWith(SpringBootTestContextBootstrapper.class)
    @ExtendWith(SpringExtension.class)
    public @interface SpringBootTest {
        
       @AliasFor("properties")
       String[] value() default {
        };
       @AliasFor("value")
       String[] properties() default {
        };
       Class<?>[] classes() default {
        };
     
       WebEnvironment webEnvironment() default WebEnvironment.MOCK;
     
       enum WebEnvironment {
        
          MOCK(false),
          RANDOM_PORT(true), 
          DEFINED_PORT(true), 
          NONE(false);
          …
       }
    }

#### 2. 官方也给出了相应的说明： ####

> If you are using JUnit 4, don’t forget to also add `@RunWith(SpringRunner.class)` to your test, otherwise the annotations will be ignored.  
> If you are using JUnit 5, there’s no need to add the equivalent `@ExtendWith(SpringExtension.class)` as `@SpringBootTest` and the other `@…Test` annotations are already annotated with it.

因此，在Spring Boot2.1.x之后单元测试可以简单的写成如下形式：

@SpringBootTest
    public class OrderServiceTest {
        
     
       @Resource
       private OrderService orderService;
     
       @Test
       public void testInsert() {
        
          Order order = new Order();
          order.setOrderNo("A001");
          order.setUserId(100);
     
          orderService.insert(order);
       }
    }

相关文章：《[SPRING BOOT JUNIT5单元测试注入BEAN抛NULLPOINTEREXCEPTION空指针异常][SPRING BOOT JUNIT5_BEAN_NULLPOINTEREXCEPTION]》

--------------------

部分参考自，对原文内容有增加：[Spring boot junit5单元测试@ExtendWith无法工作 - 程序新视界][Spring boot junit5_ExtendWith_ -]

[java - spring-boot-starter-test with JUnit 5 - Stack Overflow]: https://stackoverflow.com/questions/52862349/spring-boot-starter-test-with-junit-5
[SPRING BOOT JUNIT5_BEAN_NULLPOINTEREXCEPTION]: http://www.choupangxia.com/2019/11/13/spring-boot-junit5-null-pointer-exception/
[Spring boot junit5_ExtendWith_ -]: http://www.choupangxia.com/2019/11/13/spring-boot-junit5-extend-with/