使用 @InjectMocks 将 @Autowired 字段替换为模拟实现

Question

我想用我专门为测试创建的该类的模拟实现替换我的 Spring Boot 应用程序中的自动装配服务类。

我选择创建这个模拟实现是因为这个类的行为过于复杂，无法使用 mockito 进行模拟，因为它本身需要多个其他模拟。

我无法弄清楚如何将这个模拟实现注入到服务中。

这是一个最小的例子：

@Service
public class ServiceIWantToTestImpl implements ServiceIWantToTest{

    @Autowired
    ComplicatedDependency complicatedDependency;

    @Override
    public void methodUsingDependency(){
        String string = complicatedDependency.doSomething();
        System.out.println(string);
    }

}


public class MockComplicatedDependency implements ComplicatedDepencency{

    public MockComplicatedDependency(...){
        // Inject other mocked objects into this mock
    }

    public String doSomthing(){
        // This would be a mocked version of this function for testing
        return "test";
    }

}

@RunWith(MockitoJUnitRunner.class)
public class TestingTheService(){
    @InjectMock
    private static ServiceIWantToTest serviceIWantToTest = new ServiceIWantToTestImpl();

    @Mock
    ComplicatedDependency mockComplicatedDependency;

    @BeforeClass
    public static void init(){
        mockComplicatedDependency = new MockComplicatedDependency(...);
    }

    @Test
    public void testAttempt(){
        serviceIWantToTest.methodUsingDependency();  // This method calls complicatedDependency.doSomething() which does not run the mocked version in MockComplicatedDependency which I wanted to inject, and would always return null instead of the "test" string I put in this example.
    }

}

Answer 1

您是否必须使用 Mockito 注释来设置被测类的依赖关系？

如果这不是主要约束，为什么不做简单的设置并在 ServiceIWantToTestImpl 类中为 ComplicatedDependency 字段引入构造函数或设置器，并在测试中设置依赖项直接设置为您喜欢的任何 ComplicatedDependency impl，例如：

@Service
public class ServiceIWantToTestImpl implements ServiceIWantToTest {

    @Autowired
    ComplicatedDependency complicatedDependency;

    public ServiceIWantToTestImpl() {

    }

    public ServiceIWantToTestImpl(ComplicatedDependency complicatedDependency) {
        this.complicatedDependency = complicatedDependency;
    }

    @Override
    public void methodUsingDependency(){
        String string = complicatedDependency.doSomething();
        System.out.println(string);
    }
}

public class TestingTheService {

    private static ServiceIWantToTestImpl serviceIWantToTest;

    @BeforeClass
    public static void init(){
        serviceIWantToTest = new ServiceIWantToTestImpl(new MockComplicatedDependency());
    }

    @Test
    public void testAttempt() {
        serviceIWantToTest.methodUsingDependency();
    }

}

这是一种方式。

要使其与 Mockito 一起使用，您可以像这样使用 @Spy 而不是 @Mock：

@RunWith(MockitoJUnitRunner.class)
public class TestingTheService {

    @InjectMocks
    private static ServiceIWantToTestImpl serviceIWantToTest = new ServiceIWantToTestImpl();

    @Spy
    private static ComplicatedDependency complicatedDependency = new MockComplicatedDependency();

    @BeforeClass
    public static void init() {

    }

    @Test
    public void testAttempt() {
        serviceIWantToTest.methodUsingDependency();
    }

}

虽然这有点小题大做。我强烈建议您阅读 @Spy 注释的 JavaDoc，并确保它的预期用途是您的测试真正需要的。