Spring Boot 3.4.4升级后JUnit测试报jpaMappingContext元模型非空错误

问题现象 #

将Spring Boot版本从3.4.3升级到3.4.4后，某个JUnit测试抛出以下异常：

org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.actuate.health.HealthContributor]: Factory method 'dbHealthContributor' threw exception with message: Error creating bean with name 'jpaMappingContext': Metamodel must not be null

该测试在3.4.3版本下可正常运行，移除测试类中的以下代码后，3.4.4版本测试恢复正常，但暂不清楚原因：

@MockBean
EntityManagerFactory entityManagerFactory;

可复现代码 #

主类 #

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

测试代码 #

Base类

import org.apache.camel.Message;

public class Base {
    
    protected Exchange getExchange(final String body) {
        final Message message = new Message() {
            // 方法的默认实现
        };
        
        message.setBody(body);
        DefaultExchange exchange = new DefaultExchange(MyProcessorTest.EarlyConfiguration.camelContext);
        exchange.setMessage(message);
        
        return exchange;
    }
}

测试类

import jakarta.persistence.EntityManagerFactory;

@ExtendWith(SpringExtension.class)
@SpringBootTest(properties = { "test.configuration.class=MyProcessorTest" })
@EnableAutoConfiguration(exclude = { CamelAutoConfiguration.class })
class MyProcessorTest extends Base {
    
    @Test
    void test() {
        assertEquals(1, 1);
    }
    
    @TestConfiguration
    @ConditionalOnProperty(name = "test.configuration.class", havingValue = "MyProcessorTest")
    public static class EarlyConfiguration {

        @MockBean
        public static CamelContext camelContext;

        @MockBean
        EntityManagerFactory entityManagerFactory;
    }
}

pom.xml #

<parent>
    <!-- spring-boot-starter-parent 3.4.4 -->
</parent>

<properties>
    <java.version>17</java.version>
    <camel.version>4.10.2</camel.version>
</properties>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>   
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.camel.springboot</groupId>
        <artifactId>camel-spring-boot</artifactId>
        <version>${camel.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.camel</groupId>
        <artifactId>camel-jms</artifactId>
        <version>${camel.version}</version>
    </dependency>
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

application.yaml #

server:
  port: 9102

shared_root: "tmp/shared/tfd"

spring:
  datasource:
    url: jdbc:h2:mem:mydb;Mode=Oracle;NON_KEYWORDS=KEY,VALUE
    username: sa
    password: password
    driverClassName: org.h2.Driver
  jpa:
    show-sql: true
    hibernate:
      ddl-auto: none
  test:
    database:
      replace: none

问题原因分析 #

Spring Boot 3.4.4中，Actuator的数据库健康检查组件（dbHealthContributor）依赖JPA的jpaMappingContext，而jpaMappingContext需要从EntityManagerFactory获取JPA元模型（Metamodel）。

用@MockBean手动模拟EntityManagerFactory时，默认的Mock对象不会初始化元模型相关属性。3.4.3版本中，健康检查组件对元模型的校验更宽松，或者初始化顺序不同，未触发校验；但3.4.4版本强化了这部分依赖校验，导致Mock的EntityManagerFactory因缺少元模型抛出异常。

移除@MockBean EntityManagerFactory后，Spring Boot会自动配置基于H2内存数据库的真实EntityManagerFactory实例，该实例会正确初始化元模型，因此jpaMappingContext能正常创建，健康检查组件也能正常工作，测试恢复正常。

如果测试不需要操作JPA，也可考虑排除Actuator的数据库健康检查自动配置，或在测试中禁用健康检查相关配置，避免依赖EntityManagerFactory。

内容的提问来源于stack exchange，提问作者zilberman