@Configuration 유무 질문

안녕하세요,

@Bean이 있더라도,

@Configuration이 있어야만,

싱글톤이 보장된다(프록시,,,)고 알고 있습니다...

그러나 강의 중에 보면

Class TestConfig에 @Configuration이 없어도

싱글톤 처럼 작동을 하네요,,

(statefulService1 = hello.core.singleton.StatefulService@d78795

statefulService2 = hello.core.singleton.StatefulService@d78795)

해당 부분은 왜 그런지 자세한 설명 요청드립니다...

public class StatefulServiceTest {
    @Test
    void statefulServiceSingleton() {
        ApplicationContext ac = new AnnotationConfigApplicationContext(TestConfig.class);
        StatefulService statefulService1 = ac.getBean("statefulService", StatefulService.class);
        StatefulService statefulService2 = ac.getBean("statefulService", StatefulService.class);
        System.out.println("statefulService1 = " + statefulService1);
        System.out.println("statefulService2 = " + statefulService2);
        //ThreadA: A사용자 10000원 주문
        statefulService1.order("userA", 10000);
        //ThreadB: B사용자 20000원 주문
        statefulService2.order("userB", 20000);
        //ThreadA: 사용자A 주문 금액 조회
        int price = statefulService1.getPrice();
        //ThreadA: 사용자A는 10000원을 기대했지만, 기대와 다르게 20000원 출력
        System.out.println("price = " + price);
        Assertions.assertThat(statefulService1.getPrice()).isEqualTo(20000);
    }
//    @Configuration
    static class TestConfig {
        @Bean
        public StatefulService statefulService() {
            return new StatefulService();
        }
    }
}

@Test
void statefulServiceSingleton() {
    ApplicationContext ac = new AnnotationConfigApplicationContext(TestConfig.class);
    StatefulService statefulService1 = ac.getBean(StatefulService.class);
    StatefulService statefulService2 = ac.getBean(StatefulService.class);
    System.out.println("statefulService1 = " + statefulService1);
    System.out.println("statefulService2 = " + statefulService2);
    //ThreadA: A사용자 10000원 주문
    int userAPrice = statefulService1.order("userA", 10000);
    int userBPrice = statefulService2.order("userB", 10000);
    //int price = statefulService1.getPrice();
    //System.out.println("price = " + price);
    Assertions.assertThat(userAPrice).isEqualTo(10000);
}

static class TestConfig {
    @Bean
    public StatefulService statefulService() {
        System.out.println("TestConfig.statefulService");
        return new StatefulService();
    }

    @Bean
    public StatefulRepository statefulRepository() {
        System.out.println("TestConfig.statefulRepository");
        return new StatefulRepository(statefulService());
    }

}