为什么我的Spring Boot单元不能测试服务类中的load @Value属性？

@RunWith(SpringRunner.class)
@SpringBootTest
public class MyServiceTest {

    @Autowired
    private MyService myService;

    @MockBean
    private MyDependency myDependency;

    @Value("${my.property}")
    private String myProperty;

    @Before
    public void setup() {
        Mockito.when(myDependency.getSomeValue()).thenReturn("mockedValue");
        ReflectionTestUtils.setField(myService, "myProperty", myProperty);
    }

    @Test
    public void testMyService() {
        // 测试代码
    }
}

@RunWith(SpringRunner.class)
@SpringBootTest
@TestPropertySource(locations = "classpath:test.properties")
public class MyServiceTest {

    @Autowired
    private MyService myService;

    @Value("${my.property}")
    private String myProperty;

    @Test
    public void testMyService() {
        // 测试代码
    }
}

@Component
@ConfigurationProperties(prefix = "my")
public class MyConfig {

    private String property;

    // getter和setter方法

}

@Service
public class MyService {

    private final MyConfig myConfig;

    public MyService(MyConfig myConfig) {
        this.myConfig = myConfig;
    }

    public void doSomething() {
        String property = myConfig.getProperty();
        // 其他业务逻辑
    }
}