Is there a way to programatically login to using AzureAD with Cypress on PKCE flow?

Question

I want to athenticate myself (React application) using cypress.js (https://www.cypress.io/). Is there a way to do it programatically with PKCE? As i was reading and looking into all examples - all of them are using implicit flow

I was trying to use solutions like https://www.npmjs.com/package/react-adal but with no success as it needs an implicit flow to be turned on I was trying this as well: https://xebia.com/blog/how-to-use-azure-ad-single-sign-on-with-cypress/ with no success

I expected to programatically signin inside cypress and save user info and access_token to sessionStorage to be able to perform another api calls

Answer 1

I have not found a way to do this programmatically with PKCE per se, but with the MSAL 2.0 library (@azure/msal-browser on npm) I was able to fill in the account cache ahead of time so it thought it was already logged in. The process looks like this:

1. With a cy.task, send a request to Azure AD using the ROPC flow to get the tokens.

   const scopes = [
       'openid',
       'profile',
       'user.read',
       'email',
       'offline_access' // needed to get a refresh token
   ];
   const formdata = new URLSearchParams({
       'grant_type': 'password',
       'scope': scopes.join(' '),
       'client_info': 1, // returns an extra token that MSAL needs
       'client_id': aadClientId,
       'client_secret': aadClientSecret,
       'username': aadUsername,
       'password': aadPassword,
   });
   const response = await fetch(`https://login.microsoft.com/${aadTenantId}/oauth2/v2.0/token`, {
       method: 'POST',
       headers: {
           'Content-Type': 'application/x-www-form-urlencoded',
       },
       body: formdata.toString(),
   });
   const tokens = await response.json();
   

2. Transform the tokens into the cache entries that MSAL wants (based on observing it in a real browser)

   // The token tells us how many seconds until expiration;
   // MSAL wants to know the timestamp of expiration.
   const cachedAt = Math.round(new Date().getTime()/1000);
   const expiresOn = cachedAt + tokens.expires_in;
   const extendedExpiresOn = cachedAt + tokens.ext_expires_in;
   
   // We can pull the rest of the data we need off of the ID token body
   const id_token = JSON.parse(Buffer.from(tokens.id_token.split('.')[1], 'base64').toString('utf-8'));
   
   const clientId = id_token.aud;
   const tenantId = id_token.tid;
   const userId = id_token.oid;
   const name = id_token.name;
   const username = id_token.preferred_username;
   
   const environment = 'login.windows.net'; // 🤷‍♂️
   const homeAccountId = `${userId}.${tenantId}`;
   
   const cacheEntries = {};
   
   // client info
   cacheEntries[`${homeAccountId}-${environment}-${tenantId}`] = JSON.stringify({
     authorityType: 'MSSTS',
     clientInfo: tokens.client_info,
     environment,
     homeAccountId,
     localAccountId: userId,
     name,
     realm: tenantId,
     username,
   });
   
   // access token
   cacheEntries[`${homeAccountId}-${environment}-accesstoken-${clientId}-${tenantId}-${token.scope}`] = JSON.stringify({
     cachedAt: cachedAt.toString(),
     clientId,
     credentialType: "AccessToken",
     environment,
     expiresOn: expiresOn.toString(),
     extendedExpiresOn: extendedExpiresOn.toString(),
     homeAccountId,
     realm: tenantId,
     secret: tokens.access_token,
     target: tokens.scope,
   });
   
   // id token
   cacheEntries[`${homeAccountId}-${environment}-idtoken-${clientId}-${tenantId}-`] = JSON.stringify({
     clientId,
     credentialType: "IdToken",
     environment,
     homeAccountId,
     realm: tenantId,
     secret: tokens.id_token,
   });
   
   // refresh token
   cacheEntries[`${homeAccountId}-${environment}-refreshtoken-${clientId}--`] = JSON.stringify({
     clientId,
     credentialType: "RefreshToken",
     environment,
     homeAccountId,
     secret: tokens.refresh_token,
   });
   

3. Use cy.window to store those in sessionStorage or localStorage, depending on how you have MSAL configured.

   cy.task('login').then(cacheEntries => {
       cy.window().then(window => {
           for (let entry in cacheEntries) {
               window.sessionStorage.setItem(entry, cacheEntries[entry]);
           }
       });
   });
   

It's super fragile and not very pretty, but it works! The user that Cypress logs in as needs MFA to be disabled, of course.