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.

포트를 여는app.listen이 포함된 파일을 테스트 할 때 생기는 에러 포트를 분리하고 테스트를 진행하면 됨

참고
https://velog.io/@yongyongi/Jest-did-not-exit-one-second-after-the-test-run-has-completed