EADDRINUSE :::3000 in jest - jestjs

Question

I know this error means that port 3000 is already in use but I also tried a different port but I am still getting the same errors for some specific tests only.
This is the code of one of those test
describe("GET /", () => {
it("should return all genres", async() => {
await Genre.collection.insertMany([
{name: 'genre1'},
{name: 'genre2'}
]);
const res = await request(server).get('/api/genres');
expect(res.status).toBe(200);
expect(res.body.length).toBe(2);
expect(res.body.some( g => g.name === 'genre1')).toBeTruthy();
expect(res.body.some( g => g.name === 'genre2')).toBeTruthy();
});
});
Any way to solve this error?
listen EADDRINUSE :::3000
10 |
11 | const port = process.env.PORT || 3000;
> 12 | const server = app.listen(port, () => winston.info(`Listening on port ${port}...`));
| ^
13 |
14 | module.exports = server;
15 |
at Function.listen (node_modules/express/lib/application.js:618:24)
at Object.listen (index.js:12:20)
● /api/returns › Should return 400 if customerId is not given
connect ECONNREFUSED 127.0.0.1:62801
This is what i'm getting in the console

Answer 1

I think that the issue is down to not closing the server between test runs in Jest.
If you're using jest --watch to run your tests then it might help to add an afterAll handler?
Example minimal express app:
// app.js
const express = require("express");
const app = express();
// Server port
const HTTP_PORT = 3000;
// Start server
server = app.listen(HTTP_PORT, () => {
//console.log(`Server running on port ${HTTP_PORT}`);
});
// Root endpoint
app.get("/", (req, res, next) => {
res.json({"message":"Ok yah!"})
});
// Default response for any other request
app.use(function(req, res){
res.status(404);
});
module.exports = server;
Test file:
// app.test.js
const app = require('../app');
describe('GET /', () => {
let response;
it('proves Jest works', () => {
expect(1).toBe(1);
});
it('proves maths still works', () => {
expect(1+1).toBe(2);
});
});
// remembering to CLOSE the server after tests completed.
afterAll(async () => {
await app.close();
});