Supertest fails to test repeated post request

Question

I'm testing an api that creates users. The api does not allow the creation of users with the same login value. So I wrote the tests below:

const app = require('../config/express'); //exports a configured express app
const request = require('supertest');
const {populateUsers} = require('../seeders/users.seed');

beforeEach(populateUsers);//drop and populate database with some seeders

describe('POST /v1/users', () => {
  it('#Post a new user - 201 status code', (done) => {
    request(app)
        .post('/v1/users')
        .send({
                login:'user-teste-01',
                password: 'pass01'
        }).expect(201, done);           
  });
  it('#Post repeated login - 400 status code', (done) => {
    request(app)
        .post('/v1/users')
        .send({
                login:'user-teste-01',
                password: 'pass01'
        }).expect(400, done);
  });
});

The firts test works, but the second test returns the following error:

Error: expected 400 "Bad Request", got 201 "Created"

I did the tests manually and the api works correctly (returning 400 status code).

Where did I make the mistake in this test?

Answer 1

it is because you have beforeEach that reset your database. This hook will be executed in every test so in your 400 status code, you no longer have user user-teste-01 because it has been reset by beforeEach.

There are some solutions for this:

#1 Use login and password that exist in your seed

it('#Post repeated login - 400 status code', (done) => {
  request(app)
    .post('/v1/users')
    .send({
      login: 'user-exist-in-seed',
      password: 'pass01'
    }).expect(400, done);
});

#2 Create a user again before running the scenario

context('when user is already exist', function() {
  beforeEach(function() {
    // create a user `user-teste-01`
    // use beforeEach so it will be executed after seeding
  })

  it('#Post repeated login - 400 status code', (done) => {
    request(app)
      .post('/v1/users')
      .send({
        login: 'user-teste-01',
        password: 'pass01'
      }).expect(400, done);
  });
});

3 Use before instead of beforeEach for seeding

It will run once before all tests

before(populateUsers);//drop and populate database with some seeders