Jest SuperTest: Giving error in Open Handler when using setTimeout in the class-under-test - jestjs

Question

i am writing a E2E in Jest/Supertest in Nest JS (node) environment.
I have searched extensively about this pretty common error:
Jest has detected the following 1 open handle potentially keeping Jest from exiting:
Implemented every solutions suggested.
However getting this in a setTimeout method intermittently as follows:
Test Suites: 2 passed, 2 total
Tests: 6 passed, 6 total
Snapshots: 0 total
Time: 135.464 s
Ran all test suites.
Jest has detected the following 1 open handle potentially keeping Jest from exiting:
● Timeout
49 | },
50 | delay(millisecond: number) {
> 51 | return new Promise((resolve) => setTimeout(resolve, millisecond));
| ^
52 | },
53 | };
54 |
Here is my setTimeout code:
// The API
async create<T>(key: string, item: T): Promise<T> {
await this.delay(5000);
return this.createWithoutDelay(key, item);
}
// The delay method code
delay(millisecond: number) {
return new Promise((resolve) => setTimeout(resolve, millisecond));
},
My tests are very simple:
beforeAll(async () => {
jest.clearAllMocks();
......
app = moduleUnderTest.createNestApplication();
await app.init();
// Reference the server instance
server = app.getHttpServer();
});
it('Test: Create Object', async () => {
const response = await request(server).post('/object')
.send({
name: 'new-object',
});
expect(response.status).toEqual(HttpStatus.CREATED);
expect(response.body).toBeDefined();
expect(Array.isArray(response.body)).toBeFalsy();
const jsonResponse = JSON.parse(response.text);
expect(jsonResponse.name).toEqual('new-object');
});
afterAll(async () => {
await app.close();
await server.close();
});
The following are my Jest config:
module.exports = {
moduleFileExtensions: ["js", "json", "ts"],
verbose: true,
preset: "ts-jest",
rootDir: ".",
testTimeout: 15000,
fakeTimers: {
timerLimit: 15000,
},
testEnvironment: "node",
testRegex: ".e2e-spec.ts$",
transform: {
"^.+\\.(t|j)s$": "ts-jest"
},
moduleNameMapper: {
'^axios$': require.resolve('axios'),
},
};
In the Jest cmd, I am passing: --runInBand --forceExit --detectOpenHandles
Any clue shall be helpful.