How to test firebase account deletion in the context of a React App

I'm currently working on a React/Redux/Firebase App. I'm using Firebase for user authentication. I would like write a couple of tests to check if account deletion works consistently, but I'm not sure how to tackle it:

• tried using Cypress for that, but the gmail oauth login popup creates a new window, and Cypress cannot target it
• tried using Cypress with email/password authentication, but that requires redirecting to an email provider and confirming the account, which makes the whole test a bit flaky
• was thinking about using something like Jest, but not sure if it will catch all the side effects (apart from deleting the account from firebase, the app is also talking to a custom backend and in this case, deleting entries from another db)

Any suggestions?