Prisma is opening too many connections with PostgrsQL when running Jest end to end testing - jestjs

Question

I'm trying here to do end to end testing with Jest on a NestJS/GraphQL app and Prisma as my ORM.
What happens here is Prisma is opening too many connections with Postgres, I've tried to fix this problem by using prisma.$disconnect() after each test but it doesn't seem to work...
This is what I've tried so far.
import { PrismaService } from '../src/prisma.service';
describe('Users', () => {
let app: INestApplication;
const gql = '/graphql';
let prisma;
beforeEach(async () => {
prisma = new PrismaService();
const moduleFixture: TestingModule = await Test.createTestingModule({
imports: [AppModule],
}).compile();
app = moduleFixture.createNestApplication();
await app.init();
});
afterEach(async () => {
await prisma.$disconnect();
});
it('Query - Users', async () => {
//Using prisma to query database
});
});
My Prisma service (I got it from NestJS documentation Text ):
import { INestApplication, Injectable, OnModuleInit } from '#nestjs/common';
import { PrismaClient } from '#prisma/client';
#Injectable()
export class PrismaService extends PrismaClient implements OnModuleInit {
async onModuleInit() {
await this.$connect();
}
async enableShutdownHooks(app: INestApplication) {
this.$on('beforeExit', async () => {
await app.close();
});
}
}
These are the errors I'm getting after running all the tests (serially):
I've already looked through Prisma documentation but didn't find anything about how to setup properly a Jest environment with NestJS and Prisma.
Thanks for your help !

Answer 1

Explicitly instructing Prisma to open only one connection with your database should solve this issue.
You can do it by appending connection_limit=1 to your connection string.
Demo Connection String:
postgresql://USER:PASSWORD#HOST:PORT/DATABASE?schema=public&connection_limit=1
Reference to connection management in prisma should be helpful as well.