Jest did not exit one second after the test run has completed

Jest를 이용하여 테스트를 하는 와중, 다음과 같은 에러메시지가 발생하였다. Jest did not exit one second after the test run has completed. This usually means that there are asynchronous operations that weren't stopped in your tests. Consider running Jest with `--detectOpenHandles` to troubleshoot this issue. 그래서 적혀져 있는대로 --detectOpenHandles 을 붙여서 아래처럼 실행 해봤더니 똑같이 에러가 발생하였다. npm run test some.spec.ts --detectOpenHandles stackov..