Problem with authentication (Oauth) redirect

[RobertRacklBMW]

We have a web application that uses Oauth 2.0. Authentication happens via Oauth Implicit Flow. That means. The user is redirected to a login page. There he enteres username and password. And then he is redirected back to our application.

I am trying to write a Cypress test case for this. I did already read a lot about cypress.origin() command and more. But I still cannot get it to work.

  cy.visit("/frontend-web-app")  
  // browser is now automatically forwarded to our-company.com/auth  (HTTP 301)
  // in the cypress test the URL at the very top (not in my app, but the cypress browser window changes!!!)

  cy.get('#username').type(username)
  cy.get('#password').type(pass)
  cy.get('#loginButton').click()
	
  // now the browser is redirected back to to our app. Cypress also shows our app. Successfully logged in.
  // BUT THIS FAILS ????
  cy.url().should('equal', "/frontend-web-app")

  // the URL at the very top of the cypress browser still shows  our-company.com/auth   and not  /frontend-web-app   ????

The version at the top does not use cy.origin() at all. Login does work. But somehow the redirect back does not fully work. Any ideas?