MaxListenersExceededWarning occurs while testing with jest #6699
Description
Issue type:
[ * ] bug report
[ ] feature request
[ ] documentation issue
Database system/driver:
[ ] cordova
[ ] mongodb
[ ] mssql
[ ] mysql / mariadb
[ ] oracle
[ * ] postgres
[ ] cockroachdb
[ ] sqlite
[ ] sqljs
[ ] react-native
[ ] expo
TypeORM version:
[ * ] latest
[ ] @next
[ ] 0.x.x (or put your version here)
Steps to reproduce or a small repository showing the problem:
After updating typeorm to 0.2.26, I'm getting a lot of title errors when testing with jest. It does not occur at >=0.2.25.
$ node --trace-warnings node_modules/.bin/jest -i --config ./test/jest-e2e.js
(node:9509) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 error listeners added to [Client]. Use emitter.setMaxListeners() to increase limit
at _addListener (events.js:390:17)
at Client.addListener (events.js:406:10)
at Client.once (events.js:437:8)
at PostgresQueryRunner.<anonymous> (/home/hoge-api/src/driver/postgres/PostgresQueryRunner.ts:174:36)
at step (/home/hoge-api/node_modules/tslib/tslib.js:136:27)
at Object.next (/home/hoge-api/node_modules/tslib/tslib.js:117:57)
at fulfilled (/home/hoge-api/node_modules/tslib/tslib.js:107:62)
at processTicksAndRejections (internal/process/task_queues.js:97:5)
I'm using NestJS 7.4.4 as the api framework, but this issue is only caused by different versions of TypeORM.
The jest version is 26.4.2, the ts-jest version is 26.3.0, and the supertest version is 4.0.2.