My functional test

github.spec.js

const {
  test, trait, beforeEach, afterEach,
} = use('Test/Suite')('Admin/Session Github');
const nock = require('nock');

const User = use('App/Models/User');

const responses = require('./utils/responses');
const headers = require('./utils/headers');


trait('Test/ApiClient');

beforeEach(async () => {
  nock('https://api.github.com')
    .get('/user')
    .reply(200, responses.github_user);

  nock('https://api.github.com')
    .get('/user/emails')
    .reply(200, responses.github_emails);

  nock('https://github.com/login')
    .get('/oauth/authorize')
    .query(true)
    .reply(302, undefined, headers.authorize);

  nock('http://127.0.0.1:3333')
    .get('/admin/github/callback')
    .query(true)
    .reply(200);

  nock('https://github.com/login')
    .post('/oauth/access_token')
    .reply(responses.access_token.post);

  nock('https://github.com/login')
    .get('/oauth/access_token')
    .query(true)
    .reply(200, responses.access_token.get);
});

afterEach(async () => {
  await User.query().delete();
});

test('should be redirect to github url', async ({ client }) => {
  const response = await client.get('/admin/sessions/github').end();
  response.assertRedirect('/login/oauth/authorize');
});

test('should be make a new user with github data', async ({ assert, client }) => {
  const response = await client.get('/admin/github/callback').query({
    code: 'fake-code',
    state: 'fake-uid',
  }).cookie('oauth_state', 'fake-uid').end();
  response.assertStatus(200);
  response.assertText('Logged in');

  const fn = async () => {
    await User.findByOrFail('email', 'git@rocketseat.com.br');
  };

  assert.doesNotThrow(fn);
});

test('should be update user with github data', async ({ assert, client }) => {
  await User.create({
    username: 'rocketseat',
    name: 'Github Rocketseat',
    email: 'github@rocketseat.com.br',
    github_id: 1,
    github_token: 'fake-token',
  });

  const response = await client.get('/admin/github/callback').query({
    code: 'fake-code',
    state: 'fake-uid',
  }).cookie('oauth_state', 'fake-uid').end();

  response.assertStatus(200);
  response.assertText('Logged in');

  const user = (await User.findBy('github_id', 1)).toJSON();

  assert.equal(user.email, 'git@rocketseat.com.br');
  assert.equal(user.name, 'Git Rocketseat');
});

test('should not be make a new user with github data when email already registered', async ({ assert, client }) => {
  await User.create({
    username: 'rocketseat',
    name: 'Git Rocketseat',
    email: 'git@rocketseat.com.br',
  });

  const response = await client.get('/admin/github/callback').query({
    code: 'fake-code',
    state: 'fake-uid',
  }).cookie('oauth_state', 'fake-uid').end();

  response.assertStatus(200);
  response.assertText('Unable to authenticate. Try again later');

  const user = (await User.findBy('email', 'git@rocketseat.com.br')).toJSON();

  assert.isNull(user.github_id);
  assert.isNull(user.github_token);
});