Jest has detected the following 1 open handle potentially keeping Jest from exiting: TCPSERVERWRAP

Question

I am doing a basic end to end testing here, for the moment it's failing, but first I can't get rid of the open handle.

Ran all test suites.

Jest has detected the following 1 open handle potentially keeping Jest from exiting:

  ●  TCPSERVERWRAP

      40 |     }
      41 |     return request(app.getHttpServer())
    > 42 |       .post('/graphql')
         |        ^
      43 |       .send(mutation)
      44 |       .expect(HttpStatus.OK)
      45 |       .expect((response) => {

      at Test.Object.<anonymous>.Test.serverAddress (../node_modules/supertest/lib/test.js:61:33)
      at new Test (../node_modules/supertest/lib/test.js:38:12)
      at Object.obj.<computed> [as post] (../node_modules/supertest/index.js:27:14)
      at Object.<anonymous> (app.e2e-spec.ts:42:8)

import { Test, TestingModule } from '@nestjs/testing'
import { HttpStatus, INestApplication } from "@nestjs/common";
import * as request from 'supertest'
import { AppModule } from '../src/app.module'

describe('AppController (e2e)', () => {
  let app: INestApplication

  beforeEach(async () => {
    const moduleFixture: TestingModule = await Test.createTestingModule({
      imports: [AppModule],
    }).compile()

    app = moduleFixture.createNestApplication()
    await app.init()
  })

  afterAll(async () => {
    await app.close()
  })

  it('/ (GET)', () => {
    return request(app.getHttpServer())
      .get('/')
      .expect(HttpStatus.OK)
      .expect('Hello World!')
  })

  it('mutation', async () => {
    const mutation = {
      query: `mutation Create($title: String!) {
        create(title: $title) {
          id,
          title
        }
      }`,
      variables: {
        title: 'Mon programme',
      },
    }
    return request(app.getHttpServer())
      .post('/graphql')
      .send(mutation)
      .expect(HttpStatus.OK)
      .expect( (response) => {
        expect(response.body).toBe({
          id: expect.any(String),
          title: 'Mon programme',
        })
      })
  })
})

Any idea what's blocking the test runner ?

Note that, as I am using NestJs, I shouldn't need to use the .end(done) method at the end of the test.

PS: apparently I have to much code on this question and I need to add some more details, but have no clue what I can say more.

Solution 1

I still haven't found a perfect solution, but for the moment I went for this workaround :

jest --config ./test/jest-e2e.json --forceExit

The forceExit option kill the openHandles somehow and unlock everything. Yet, I still looking for the "proper way" of handling that issue.

Solution 2

Instead of it try using test and pass done as a parameter and call that. This worked for me.

test('mutation', async (done) => {
    const mutation = {
      query: `mutation Create($title: String!) {
        create(title: $title) {
          id,
          title
        }
      }`,
      variables: {
        title: 'Mon programme',
      },
    }
    const response = request(app.getHttpServer())
      .post('/graphql')
      .send(mutation)
     expect(response).to.be(HttpStatus.Ok)
     done()
  })

Solution 3

You are re-creating the whole app again beforeEach, but tearing it down only in afterAll, which means you are probably leaking some memory along the way. You are assigning a new instance to the app variable, but there are most likely hidden references that prevent the garbage colletor from clearing the previous instance - like the reference that the request function got.

Change beforeEach to beforeAll and you should be good to go.

Comments

[A Mehmeto]

Thank for the answer. But unfortunately it has no effect.

[Papooch]

@AMehmeto hm, strange, are you running multiple tests in parallel or just one file?

[A Mehmeto]

Just one file only.

[Papooch]

@AMehmeto my second guess is that something is happening within your app that keeps it from exiting. Have you read through this thread, expecially the linked comment?

[Patrick]

thank you so much I have spent hours trying to mock the setInterval() function causing problems but it didn't work. This is an easy, simple fix.

[Admin]

As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center.

[guero64]

No joy here. So far only the --forceExit options works for me.

[David]

it and test are the same

[Florian Koch]

Actually there are two approaches mixed here, either use async or the done callback. You will notice using both isn't possible in Typescript, where it refuses to run this code.

[fadingbeat]

Nice job! Your hourly research has helped me :)

[Akif Kara]

I had --forceExit and --detectOpenHandles in my script after removed --detectOpenHandles it solved "test:e2e": "jest --config ./test/jest-e2e.json --forceExit"