CODEWITHSUNDEEP
node.jsexpressjestjs
NickW
NickW

Reputation: 1343

Server instances, jest and 'listen EADDRINUSE :::3000'

Am new to jest, node and express, and am having a problem with testing my app.

The actual code seems to be working - it's just when passing the server instance to each of the test files (user.test.js and genres.test.js) and running jest, the port is being blocked. I assume it's because I'm creating duplicate instances of the server in each test file, without realising it.

Running jest with the flag --runInBand works, and so does only using one test file, but this doesn't help me understand exactly what's going on.

I've posted example code below, but I'm struggling to cut it down, however I do think most of the code is irrelevant, and it's just down to how I'm passing the server to each file.

Again, apologies for the length, but I think it should be very basic for anyone but me! Thanks.

index.js (.)

const express = require('express');
const app = express();
const genres = require('./routes/genres');
const users = require('./routes/users');
app.use(express.json());
app.use('/api/genres', genres);
app.use('/api/users', users);

const port = process.env.PORT || 3000;

const server = app.listen(port, () => console.log(`Listening on port ${port}...`));
console.log(typeof server);
// export server to be used in test file
module.exports = server;

genres.js (./routes)

const express = require('express');
const router = express.Router();

router.post('/', async (req, res) => {
    res.send('post genre ok');
});

module.exports = router;

users.js (./routes)

const express = require('express');
const router = express.Router();

router.post('/', async (req, res) => {
    res.send('post user ok');
});

module.exports = router;

genres.test.js (./tests)

const request = require('supertest');

let server;

describe('auth tests', () => {

    const exec = async function(){
        return await request(server)
            .post('/api/genres');
    };

    beforeEach(() => {
        server = require('../index');
    });
    afterEach(async () => {
        await server.close();
    });

    describe('POST /', () => {
        it('should return 200', async () => {
            const res = await request(server).post('/api/genres');
            expect(res.status).toBe(200);
        });
    });
});

user.test.js (./tests)

const request = require('supertest');

let server;

describe('user tests', () => {

    const exec = async function(){
        return await request(server)
            .post('/api/user');
    };

    beforeEach(() => {
        server = require('../index');
    });
    afterEach(async () => {
        await server.close();
    });

    describe('POST /', () => {
        it('should return 200', async () => {
            const res = await request(server).post('/api/users');
            expect(res.status).toBe(200);
        });
    });
});

Upvotes: 1

Views: 2130

Answers (1)

NickW
NickW

Reputation: 1343

Hopefully this (point 2) helps others with this question

It has worked for me, by splitting the app from the server. I'm not sure if this is the right approach, and I'm not 100% sure why it works with the app rather than the server, but all my tests are now passing.

index.js is now app.js:

const express = require('express');
const app = express();
const genres = require('./routes/genres');
const users = require('./routes/users');
app.use(express.json());
app.use('/api/genres', genres);
app.use('/api/users', users);

// export server to be used in test file
module.exports = app;

The server is separated into another file:

const app = require('./app');

const port = process.env.PORT || 3000;

app.listen(port, () => console.log(`Listening on port ${port}...`));

and then the test files import the app rather than the server. therefore each test doesn't create its own instance.

NB: I think - I don't really know how correct this is, but as mentioned, it works

Upvotes: 5

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