Jest promise not resolving - express

Question

I am testing my express server in Jest. All test pass but Jest doesn't close or exit. I have no idea why but I believe my server is closing after the test runs. I tried running yarn jest --detectOpenHandles and the response came back saying "Jest has detected the following 1 open handle potentially keeping Jest from exiting:
Promise"
Here is my code...
const request = require('supertest');
const app = require('../server');
const server = app.listen(8000, '127.0.0.1');
afterAll(() => {
server.close();
});
describe('GET /', () => {
it('should respond with JSON (list of all users)', async () => {
try {
const response = await request(server).get('/')
.expect('Content-Type', /json/);
expect(response.statusCode).toBe(200);
} catch (e) {
console.log(e);
}
});
});
I can't seem to understand why the promise isn't resolving if that's actually the issue. My express app is pulling data from Firebase and returning the data once a get request is made. Any ideas on what's going on?
In Server.js file I connect to Firebase maybe this is the issue?
const db = admin.database();
const ref = db.ref('users');
app.get('/', (req, res) => {
// Attach an asynchronous callback to read the data at our posts reference
ref.on('value', function(snapshot) {
res.send(parseUsers(snapshot.val()));
res.status(200);
}, function (errorObject) {
res.send([],'The read failed: ' + errorObject.code);
res.status(500);
});
} );