I am new to unit testing using Mocha and Chai. I am trying to implement the unit testing on a REST-API which is written using Node.js and MongoDB. I have tried one tutorial but I'm getting AssertionError: expected { Object (driver, name, ...) } to have property '_id' when I run npm test. Mainly it should enter the data into MongoDB.

app.js

const express = require('express');

const bodyParser = require('body-parser');

const app = express();



const Note = require('./db/models/note.js').Note;



app.use(bodyParser.json());



app.get('/notes', (req, res) => {

  Note.find()

    .then((notes) => res.status(200).send(notes))

    .catch((err) => res.status(400).send(err));

});



app.post('/notes', (req, res) => {

  const body = req.body;

  const note = new Note({

    name: body.name,

    text: body.text

  });

  note.save(note)

    .then((note) => res.status(201).send(note))

    .catch((err) => res.status(400).send(err));

});



module.exports = app;

test.js

process.env.NODE_ENV = 'test';



const expect = require('chai').expect;

const request = require('supertest');



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

const conn = require('../../../db/index.js');



describe('POST /notes', () => {

  before((done) => {

    conn.connect()

      .then(() => done())

      .catch((err) => done(err));

  })



  after((done) => {

    conn.close()

      .then(() => done())

      .catch((err) => done(err));

  })



  it('OK, creating a new note works', (done) => {

    request(app).post('/notes')

      .send({ name: 'NOTE Name', text: AAA })

      .then((res) => {

        const body = res.body;

        expect(body).to.contain.property('_id');

        expect(body).to.contain.property('name');

        expect(body).to.contain.property('text');

        done();

      })

      .catch((err) => done(err));

  })



  it('Fail, note requires text', (done) => {

    request(app).post('/notes')

      .send({ name: 'NOTE' })

      .then((res) => {

        const body = res.body;

        expect(body.errors.text.name)

          .to.equal('ValidatorError')

        done();

      })

      .catch((err) => done(err));

  });

})