如何在 Spring 引导单元测试中使用依赖注入？

Question

是否可以使用 Spring Boot 将依赖注入与单元测试结合使用？对于集成测试 @SpringBootTest 启动整个应用程序上下文和容器服务。但是是否可以在单元测试粒度上启用依赖注入功能？

这是示例代码

@ExtendWith(SpringExtension.class)
public class MyServiceTest {
    
    @MockBean
    private MyRepository repo;
    
    @Autowired
    private MyService service; // <-- this is null
    
    @Test
    void getData() {
        MyEntity e1 = new MyEntity("hello");
        MyEntity e2 = new MyEntity("world");
        
        Mockito.when(repo.findAll()).thenReturn(Arrays.asList(e1, e2));
        
        List<String> data = service.getData();
        
        assertEquals(2, data.size());
    }
}

@Service
public class MyService {
    
    private final MyRepository repo; // <-- this is null
    
    public MyService(MyRepository repo) {
        this.repo = repo;
    }
    
    public List<String> getData() {
        return repo.findAll().stream()
                .map(MyEntity::getData)
                .collect(Collectors.toList());
    }
}

或者我是否应该将 SUT（服务 class）作为 POJO 进行管理并手动注入模拟的依赖项？我想保持快速测试但尽量减少样板代码。

Answer 1

您还没有为 MyRepository

添加 @Autowired 服务

服务Class

@Service
public class MyService {
    
    private final MyRepository repo; // <-- this is null
    
    @Autowired
    public MyService(MyRepository repo) {
        this.repo = repo;
    }
    
    public List<String> getData() {
        return repo.findAll().stream()
                .map(MyEntity::getData)
                .collect(Collectors.toList());
    }
}

服务测试Class

@ExtendWith(MockitoExtension.class)
public class MyServiceTest {
    
    @Mock
    private MyRepository repo;
    
    @InjectMocks
    private MyService service;
    
    @Test
    void getData() {
        MyEntity e1 = new MyEntity("hello");
        MyEntity e2 = new MyEntity("world");
        
        Mockito.when(repo.findAll()).thenReturn(Arrays.asList(e1, e2));
        
        List<String> data = service.getData();
        
        assertEquals(2, data.size());
    }
}

Answer 2

正如评论中提到的@M.Deinum，单元测试不应该使用依赖注入。使用 Mockito（和 Junit5）模拟 MyRepository 并注入 MyService：

@ExtendWith(MockitoExtension.class)
public class MyServiceTest {

    @InjectMocks
    private MyService service;

    @Mock
    private MyRepository repo;

    @Test
    void getData() {
        MyEntity e1 = new MyEntity("hello");
        MyEntity e2 = new MyEntity("world");

        Mockito.when(repo.findAll()).thenReturn(Arrays.asList(e1, e2));

        List<String> data = service.getData();

        assertEquals(2, data.size());
    }
}

如果要测试存储库，请使用 @DataJpaTest。来自 docs:

Using this annotation will disable full auto-configuration and instead apply only configuration relevant to JPA tests.

@DataJpaTest
public class MyRepositorTest {

    @Autowired
    // This is injected by @DataJpaTest as in-memory database
    private MyRepository repo;

    @Test
    void testCount() {
        repo.save(new MyEntity("hello"));
        repo.save(new MyEntity("world"));

        assertEquals(2, repo.count());
    }
}

总而言之，建议的方法是使用 Mockito（或类似库）测试模拟存储库层的服务层，并使用 @DataJpaTest.

测试存储库层

如何在 Spring 引导单元测试中使用依赖注入？

How to use Dependency Injection with Spring Boot Unit Testing?

java

spring

unit-testing

mockito

spring-boot