How to test single page application with Cypress and Auth0

I am having a single page application hidden behind Auth0 lock, using @auth0/auth0-spa-js. I would like to test it using Cypress, so I have decided to follow the official Auth0 blog post, as well as Johnny Reilly blog post.

I am able to successfully retrieve valid JWT token from auth0 using suggested request. I have no idea what to do with it :(

The trouble I am facing is that both of the above approaches are relying on the app to store the JWT token locally (either in cookie or localstorage). The @auth0/auth0-spa-js is, however, using a different approach, and I assume all the relevant cookies/localstorage is stored on auth0 domains.

Do you have any idea, if there is a way to get around it?

There is a similar issue reported here raised in July 2018, not really providing any solution

I found a resolved issue on @auth0/auth0-spa-js github. The approach suggested by cwmrowe seems to be working

The solution is to mock the response of oauth/token endpoint with token generated on e2e test side.

The approach seems to be working for us

I am copying over the sample code cwmrowe has provided

Cypress.Commands.add(
  'login',
  (username, password, appState = { target: '/' }) => {
    cy.log(`Logging in as ${username}`);
    const options = {
      method: 'POST',
      url: Cypress.env('Auth0TokenUrl'),
      body: {
        grant_type: 'password',
        username,
        password,
        audience: Cypress.env('Auth0Audience'),
        scope: 'openid profile email',
        client_id: Cypress.env('Auth0ClientId'),
        client_secret: Cypress.env('Auth0ClientSecret')
      }
    };
    cy.request(options).then(({ body }) => {
      const { access_token, expires_in, id_token } = body;

      cy.server();

      // intercept Auth0 request for token and return what we have
      cy.route({
        url: 'oauth/token',
        method: 'POST',
        response: {
          access_token,
          expires_in,
          id_token,
          token_type: 'Bearer'
        }
      });

      // Auth0 SPA SDK will check for value in cookie to get appState
      // and validate nonce (which has been removed for simplicity)
      const stateId = 'test';
      const encodedAppState = encodeURI(JSON.stringify(appState));
      cy.setCookie(
        `a0.spajs.txs.${stateId}`,
        `{%22appState%22:${encodedAppState}%2C%22scope%22:%22openid%20profile%20email%22%2C%22audience%22:%22default%22}`
      );

      const callbackUrl = `/auth/callback?code=test-code&state=${stateId}`;
      return cy.visit(callbackUrl);
    });
  }
);

declare namespace Cypress {
  interface Chainable<Subject> {
    login(
      username: string,
      password: string,
      appState?: any
    ): Chainable<Subject>;
  }
}