java - 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类的模拟实现替换我的 spring boot 应用程序中服务的 Autowiring 类。

我选择创建这个模拟实现是因为此类的行为太复杂而无法使用 mockito 进行模拟，因为它本身需要多个其他模拟。

我不知道如何将这个模拟的实现注入(inject)到服务中。

这是这种情况的一个最小示例:

@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

是否必须使用 Mockito 注释来为被测类设置依赖项？

如果这不是主要约束，为什么不进行简单的设置并在 ServiceIWantToTestImpl 中引入构造函数或 setter？ ComplicatedDependency 的类字段并将测试设置中的依赖项直接设置为您喜欢的 ComplicatedDependency 的任何含义，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。

要让它与 Mockito 一起工作，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hack。我强烈建议您阅读 @Spy 注释的 JavaDoc，并确保它的预期用途是您测试真正需要的。