TDD for Authors' Haven - Team Elven

user.test.js

import chai from 'chai';
import supertest from 'supertest';
import app from '../app';

const request = supertest(app);
const { expect } = chai;

// existing user email
// invalid email
// password of length less than 8
// password not being alphanumeric
// successful sign up

describe('Test user API', () => {
  it('should return a status 400 error if email already exist', (done) => {
      request
        .post('/api/users')
        .set('Content-type', 'application/json')
        .send({
          username: 'Fayokemi',
          email: '[email protected]',
          password: 'signup49test',
        })
        .end((err, res) => {
          expect(res.status).to.equal(400);
          expect(res.body).to.be.an('object');
          expect(res.body).to.haveOwnProperty('errors').to.be.an('array');
          expect(res.body.errors.email[0]).to.equal('The email you have entered already exist');
          done();
        });
    });
  
  it('should return a status 400 error response for invalid email format', (done) => {
      request
        .post('/api/users')
        .set('Content-type', 'application/json')
        .send({
          username: 'Fayokemi',
          email: 'fayoarightcom',
          password: 'signup49test',
        })
        .end((err, res) => {
          expect(res.status).to.equal(400);
          expect(res.body).to.be.an('object');
          expect(res.body).to.be.an('array');
          expect(res.body.errors.email[1]).to.equal('The email you have entered is invalid');
          done();
        });
    });
  
  it('should return a status 400 error if the password length is less than 8', (done) => {
      request
        .post('/api/users')
        .set('Content-type', 'application/json')
        .send({
          username: 'Fayokemi',
          email: '[email protected]',
          password: 'sign',
        })
        .end((err, res) => {
          expect(res.status).to.equal(400);
          expect(res.body).to.be.an('object');
          expect(res.body).to.haveOwnProperty('errors').to.be.an('array');
          expect(res.body.errors.password[0]).to.equal('Password length may not be less than 8');
          done();
        });
    });
  
   it('should return a status 400 error if the password is not Alphanumeric', (done) => {
      request
        .post('/api/users')
        .set('Content-type', 'application/json')
        .send({
          username: 'Fayokemi',
          email: '[email protected]',
          password: 'signeduptoday',
        })
        .end((err, res) => {
          expect(res.status).to.equal(400);
          expect(res.body).to.be.an('object');
          expect(res.body.errors).to.be.an('array');
          expect(res.body).to.haveOwnProperty('errors').to.be.an('array');
          expect(res.body.errors.password[1]).to.equal('The password field should contain both letters and numerals');
          done();
        });
    });
  
   it('should return a status 200 for successfully signing up', (done) => {
     
     let username;
     let firstName;
     let password;
     
      request
        .post('/api/users')
        .set('Content-type', 'application/json')
        .send({
          username: 'Fayokemi',
          email: '[email protected]',
          password: 'signed49test7',
        })
        .end((err, res) => {
          expect(res.status).to.equal(400);
          expect(res.body).to.be.an('object');
          expect(res.body).to.haveOwnProperty('message').to.equal(`Success signing up ${username}`);
          expect(res.body.email).to.equal(`${email}`);
          expect(res.body.password).to.equal(`${password}`);
          done();
        });
    });
})

Good job on the test.
Echoing what everybody else has said, I feel the responses are too wordy. Try and make then more concise next time.