섹션 5

@Test
@DisplayName("싱글톤의 주의할 점")
void statefulServiceSingleton() {
    ApplicationContext ac = new AnnotationConfigApplicationContext(TestConfig.class);
    StatefulService statefulService1 = ac.getBean("testConfig", StatefulService.class);
    StatefulService statefulService2 = ac.getBean("testConfig", StatefulService.class);

    statefulService1.order("userA", 10000);
    statefulService2.order("userB", 20000);

    assertThat(statefulService2.getPrice()).isSameAs(20000);
}

오류 메시지
java.lang.AssertionError: 
Expecting actual:
  20000
and:
  20000
to refer to the same object

이렇게 테스트 했더니 오류가 뜹니다!ㅠㅠㅠ

Assertions.assertThat().isSameAs()

Assertions.assertThat().isEqualsTo()

두 개의 차이점이 궁금합니다!