Why Uncaught AssertionError: expected 404 to equal 200 and not Uncaught AssertionError: expected [Error: Not Found] to not exist?

Question

Node.js

Hello, I'm trying to deal with restAPI, I was advised this article, for step-by-step execution:

process.env.NODE_ENV = 'test';

const chai = require('chai');
const should = chai.should();
const chaiHttp = require('chai-http');
chai.use(chaiHttp);

const server = require('../src/server/index');
const knex = require('../src/server/db/connection');

describe('routes : movies', () => {

    beforeEach(() => {
        return knex.migrate.rollback()
            .then(() => {
                return knex.migrate.latest();
            })
            .then(() => {
                return knex.seed.run();
            });
    });

    afterEach(() => {
        return knex.migrate.rollback();
    });
});

describe('GET /api/v1/movies', () => {
    it('should return all movies', (done) => {
        chai.request(server)
            .get('/api/v1/movies')
            .end((err, res) => {
                // there should be no errors
                should.not.exist(err);
                // there should be a 200 status code
                res.status.should.equal(200);
                // the response should be JSON
                res.type.should.equal('application/json');
                // the JSON response body should have a
                // key-value pair of {"status": "success"}
                res.body.status.should.eql('success');
                // the JSON response body should have a
                // key-value pair of {"data": [3 movie objects]}
                res.body.data.length.should.eql(3);
                // the first object in the data array should
                // have the right keys
                res.body.data[0].should.include.keys(
                    'id', 'name', 'genre', 'rating', 'explicit'
                );
                done();
            });
    });
});

describe('GET /api/v1/movies/:id', () => {
  it('should respond with a single movie', (done) => {
    chai.request(server)
    .get('/api/v1/movies/1')
    .end((err, res) => {
      // there should be no errors
      should.not.exist(err);
      // there should be a 200 status code
      res.status.should.equal(200);
      // the response should be JSON
      res.type.should.equal('application/json');
      // the JSON response body should have a
      // key-value pair of {"status": "success"}
      res.body.status.should.eql('success');
      // the JSON response body should have a
      // key-value pair of {"data": 1 movie object}
      res.body.data[0].should.include.keys(
        'id', 'name', 'genre', 'rating', 'explicit'
      );
      done();
    });
  });
});

The author says that the result of the tests should be: Uncaught AssertionError: expected [Error: Not Found] to not exist,
but I get Uncaught AssertionError: expected 404 to equal 200, why? Thank you

Answer 1

Because for request 404 this is not an error, but a completely valid response. An error, for example, will be something network, such as the inability to connect or a timeout.