使用@MockBean模拟Mapper的Spring Boot测试失败问题排查

问题描述 #

开发Spring Boot应用时，尝试用@MockBean编写服务层测试以避免连接数据库。测试中模拟CartMapper的countCarts方法返回1，但断言失败，实际返回数据库真实数据5，说明@MockBean未生效。测试上下文配置类TestApplication带有@MapperScan注解，移除该注解后，又出现AddressMapper等Bean无法找到的错误，需要解决该问题。

测试代码 #

// CartServiceImpl中的countCarts方法
//    @Override
//    public int countCarts(Cart cart) {
//        return cartMapper.countCarts(cart);
//    }

@SpringBootTest(classes = TestApplication.class)
@AutoConfigureMockMvc
class CartServiceImplTest {
    @MockBean
    private CartMapper cartMapper;
    @Autowired
    private CartServiceImpl cartService;
    @Test
    void testCountCarts() {
        Cart cart = new Cart();
        int count = 1;
        when(cartMapper.countCarts(Mockito.any())).thenReturn(count);
        assertEquals(count, cartService.countCarts(cart));
        //verify(cartMapper).countCarts(cart);
    }
}

断言失败错误信息 #

Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 3.777 s <<< FAILURE! - in CartServiceImplTest
testCountCarts  Time elapsed: 0.809 s  <<< FAILURE!
org.opentest4j.AssertionFailedError: expected: <1> but was: <5>
    at CartServiceImplTest.testCountCarts(CartServiceImplTest.java:46)

测试上下文配置类 #

@ComponentScan(basePackages = {"world.xuewei"}, excludeFilters = {@ComponentScan.Filter(classes = {SpringBootApplication.class})
})
@SpringBootConfiguration
@EnableAutoConfiguration
@MapperScan(basePackages = {"world.xuewei.mapper"})
public class TestApplication {
    public static void main(String[] args) {
        SpringApplication.run(TestApplication.class, args);
    }

}

移除@MapperScan后的错误信息 #

java.lang.IllegalStateException: Failed to load ApplicationContext
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'addressController': Unsatisfied dependency expressed through field 'addressService'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'addressService': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'world.xuewei.mapper.AddressMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@javax.annotation.Resource(shareable=true, lookup="", name="", description="", authenticationType=CONTAINER, type=java.lang.Object.class, mappedName="")}

解决方案 #

原因分析 #

@MapperScan会触发MyBatis生成真实的Mapper实例，而Spring中@MockBean的优先级低于MyBatis自动生成的Bean，导致真实的CartMapper被注入到CartServiceImpl中，Mock配置完全失效。

具体解决办法 #

办法一：排除数据库与MyBatis自动配置

在测试类的@SpringBootTest注解中，排除数据源和MyBatis相关的自动配置类，避免Spring初始化真实的数据库连接和Mapper实例：

@SpringBootTest(classes = TestApplication.class, exclude = {
    DataSourceAutoConfiguration.class,
    MybatisAutoConfiguration.class,
    DataSourceTransactionManagerAutoConfiguration.class
})
@AutoConfigureMockMvc
class CartServiceImplTest {
    // 原有测试代码不变
}

此时@MockBean的CartMapper会被正确注入，若其他Service依赖的Mapper也需要Mock，只需给对应的Mapper添加@MockBean即可。

办法二：给@MapperScan添加环境条件

修改TestApplication的配置，让@MapperScan仅在非测试环境生效：

@ComponentScan(basePackages = {"world.xuewei"}, excludeFilters = {@ComponentScan.Filter(classes = {SpringBootApplication.class})
})
@SpringBootConfiguration
@EnableAutoConfiguration
@Profile("!test") // 仅在非test环境启用Mapper扫描
@MapperScan(basePackages = {"world.xuewei.mapper"})
public class TestApplication {
    public static void main(String[] args) {
        SpringApplication.run(TestApplication.class, args);
    }
}

然后在测试类中激活test环境：

@SpringBootTest(classes = TestApplication.class)
@AutoConfigureMockMvc
@ActiveProfiles("test") // 激活测试环境
class CartServiceImplTest {
    @MockBean
    private CartMapper cartMapper;
    @MockBean
    private AddressMapper addressMapper; // 其他需要的Mapper也Mock
    @Autowired
    private CartServiceImpl cartService;
    
    // 原有测试代码不变
}

办法三：脱离Spring上下文，用Mockito直接测试

无需加载完整的Spring上下文，改用Mockito的扩展类直接测试Service，速度更快且无环境冲突：

@ExtendWith(MockitoExtension.class)
class CartServiceImplTest {
    @Mock // 模拟Mapper实例
    private CartMapper cartMapper;
    @InjectMocks // 自动将Mock的Mapper注入到Service中
    private CartServiceImpl cartService;

    @Test
    void testCountCarts() {
        Cart cart = new Cart();
        int count = 1;
        when(cartMapper.countCarts(Mockito.any())).thenReturn(count);
        assertEquals(count, cartService.countCarts(cart));
        verify(cartMapper).countCarts(cart); // 验证方法是否被调用
    }
}

内容的提问来源于stack exchange，提问作者Cillian