@PostConstruct and bean created with new in configuration class

I have a service in spring boot with a @PostConstruct method. In some integration tests, this method shall not be executed (the service is not used at all in these integratoin tests). So I thought I could just let the bean be created with new inside a configuration class loaded inside this test (@ContextConfiguration).

However, this does not work as I thought. @PostConstruct is called anyway, even twice, as you can see below (yes, this is the whole code):

Application

@SpringBootApplication
public class DemoApplication {

  public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
  }
}

Service

@Service
public class MyService {

  @PostConstruct
  public void startup() {
    System.out.println("@PostConstruct - " + this);
  }
}

Test

@RunWith(SpringRunner.class)
@SpringBootTest(
    webEnvironment = WebEnvironment.RANDOM_PORT,
    classes = {DemoApplication.class})
@ContextConfiguration(classes = TestConfiguration.class)
public class DemoApplicationTests {

  @Test
  public void test() {
    System.out.println("Test");
  }

  @Configuration
  static class TestConfiguration {

    @Bean
    public MyService xxx() {
      MyService myService = new MyService();
      System.out.println("@Bean - " + myService);
      return myService;
    }

  }
}

If the test is executed, the following output is printed:

 :: Spring  Boot ::        (v2.1.1.RELEASE)
...
2018-11-30  20:34:28.422  INFO 16916 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-11-30  20:34:28.422  INFO 16916 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1573 ms
@PostConstruct  - com.example.demo.MyService@41c89d2f
@Bean - com.example.demo.MyService@2516fc68
@PostConstruct  - com.example.demo.MyService@2516fc68
2018-11-30  20:34:28.838  INFO 16916 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2018-11-30  20:34:29.086  INFO 16916 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 62040 (http) with context path ''
2018-11-30  20:34:29.090  INFO 16916 --- [           main] com.example.demo.DemoApplicationTests    : Started DemoApplicationTests in 2.536 seconds (JVM running for 4.187)
Test
2018-11-30  20:34:29.235  INFO 16916 --- [       Thread-3] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'

Can anybody explain me this?

• why is first @PostConstruct called
• why is secondly @PostConstruct called for a bean constructed with new. Why is this bean managed by spring?
• How can I achieve what I need?