Java SpringBoot中如何Mock final类ServiceBusReceiverAsyncClient做单元测试？

方案一：启用Mockito MockMaker Inline #

Mockito 2.x及以上版本支持mock final类，只需添加简单配置即可：

• 在测试资源目录src/test/resources下创建mockito-extensions文件夹，新建文件org.mockito.plugins.MockMaker，内容写入：

mock-maker-inline

配置完成后，修正原有测试代码的语法错误即可正常运行：

@Mock
private ServiceBusReceiverFactory factory;

@Test
void test() {
    ServiceBusReceiverAsyncClient mockedReceiver = Mockito.mock(ServiceBusReceiverAsyncClient.class);
    when(this.factory.getClient()).thenReturn(mockedReceiver);
 
    consumer.listen(ack);
    // 触发ServiceBusReceiverAsyncClient.receivedMessages()调用，进而触发ack逻辑

    verify(ack, atLeastOnce()).success();
}

方案二：封装自定义接口隔离依赖 #

如果不想修改Mockito配置，可以通过封装接口的方式隔离对final类的直接依赖：

1. 定义业务所需的接口：

public interface MessageReceiverClient {
    Flux<ServiceBusReceivedMessage> receivedMessages();
    // 按需添加其他业务需要调用的方法
}

2. 实现类包装原ServiceBus客户端：

public class ServiceBusMessageReceiverClient implements MessageReceiverClient {
    private final ServiceBusReceiverAsyncClient client;

    public ServiceBusMessageReceiverClient(ServiceBusReceiverAsyncClient client) {
        this.client = client;
    }

    @Override
    public Flux<ServiceBusReceivedMessage> receivedMessages() {
        return client.receivedMessages();
    }
}

3. 修改业务代码依赖MessageReceiverClient接口，测试时直接mock该接口：

@Mock
private ServiceBusReceiverFactory factory;
@Mock
private MessageReceiverClient mockedReceiver;

@Test
void test() {
    when(this.factory.getClient()).thenReturn(new ServiceBusMessageReceiverClient(Mockito.mock(ServiceBusReceiverAsyncClient.class)));
    when(mockedReceiver.receivedMessages()).thenReturn(Flux.just(new ServiceBusReceivedMessage(...))); // 模拟消息返回

    consumer.listen(ack);

    verify(ack, atLeastOnce()).success();
}

方案三：使用PowerMock（兼容旧版本，不推荐） #

如果项目依赖的Mockito版本较低，可通过PowerMock实现final类的mock：

1. 引入PowerMock相关依赖（根据Maven/Gradle调整）
2. 测试类添加注解并编写测试：

@RunWith(PowerMockRunner.class)
@PrepareForTest(ServiceBusReceiverAsyncClient.class)
public class YourConsumerTest {
    @Mock
    private ServiceBusReceiverFactory factory;

    @Test
    void test() {
        ServiceBusReceiverAsyncClient mockedReceiver = PowerMockito.mock(ServiceBusReceiverAsyncClient.class);
        when(this.factory.getClient()).thenReturn(mockedReceiver);
 
        consumer.listen(ack);

        verify(ack, atLeastOnce()).success();
    }
}

内容的提问来源于stack exchange，提问作者Matheus Weber