Couldn't run e2e tests in parallel NestJS

[kevindavee]

Describe the bug
I want to run my jest e2e test in parallel. I run the migration on the App module onModuleInit. I initialized the Testing Module in beforeAll of my test file. I didn't run the jest test using --runInBand because in the CI, I would like to have the test running in parallel. But I got UniqueConstraintViolationException: create database "test" - duplicate key value violates unique constraint "pg_database_datname_index". Am I setting up the e2e test environment correctly?

app.module.ts

async onModuleInit(): Promise<void> {
  await this.orm.getMigrator().up();
}

*.e2e-spec.ts

beforeAll(async () => {
  const module: TestingModule = await Test.createTestingModule({
      imports: [AppModule],
   }).compile();
  const app = module.createNestApplication();
  await app.init()
});

To Reproduce
Steps to reproduce the behavior:

1. Have the migrator run in onModuleInit
2. Have more than 1 test file.

Expected behavior
I wanted to have my e2e tests running in parallel, and have my test database teared down everytime the test is finished.

Versions

Dependency	Version
node	18
typescript	4.3.5
mikro-orm	5.6.1
postgres	5.6.1

[B4nan]

You either need to implement some locking in the onModuleInit method, so you ensure the migrations are never executed in parallel, or just run the migrations first before you run the tests. Or have a dedicated database for each test, that is the most correct solution to me if you want to test things on a real database in parallel.

[kevindavee]

A dedicated database for each test is not feasible. If I want to run in parallel using ten workers, I have to run 10 DB simultaneously. I'll try to run the migrations first before I run the tests. I think that's the most feasible so far.