Q:

Jest did not exit one second after the test run has completed when using supertest and mongoose

I am using jest to test my node.js endpoints with supertest.
However after running my test jest does not exit, instead it returns the following and hangs:

Jest did not exit one second after the test run has completed.
This usually means that there are asynchronous operations that weren't
  stopped in your tests. Consider running Jest with
  --detectOpenHandles to troubleshoot this issue.

import request from "supertest";
import server from "../../src/index";
import mongoose from "mongoose";

describe("Authentication", () => {

    beforeAll( async () => {
        console.log("Test Starting...");
        await mongoose.connection.dropDatabase();
    });

    afterAll( async () => {
        console.log("... Test Ended");
        await mongoose.connection.dropDatabase();
        await mongoose.connection.close();
    });

    it("should authenticate with basic auth", async (done) => {

        const BASIC_AUTH = Buffer.from(TEST_VARIABLES.HS_USERNAME + ":" + TEST_VARIABLES.HS_PASSWORD).toString("base64");

        const auth_response = await request(server).get("/api/v2/auth/admin")
            .set("Authorization", "Basic " + BASIC_AUTH)
            .expect(200);

        done();

    });

A:

The app is the node.js server is still listening.
server = app.listen(this.config.port, "0.0.0.0");

adding server.close() to afterAll solved the problem.
  afterAll( async () => {
        console.log("... Test Ended");
        await mongoose.connection.dropDatabase();
        await mongoose.connection.close();
        app.close()
    });

