Test Stripe credit card filling with Cypress, depends on https://gist.github.com/loranmutafov/0aef48884f3ec05edeb95aa1e0d06a17

stripe.commands.js

Cypress.Commands.add('fillOutCreditCardForm', details => {
  cy.get('.__PrivateStripeElement > iframe')
    .iframe()
    .then(iframes => {
      cy.wrap(iframes[0])
        .find('.InputElement')
        .first()
        .type(details.number);
      cy.wrap(iframes[1])
        .find('.InputElement')
        .first()
        .fill(
          details.expiration ||
          moment()
            .add(5, 'years')
            .format('MM/YY')
        );
      cy.wrap(iframes[2])
        .find('.InputElement')
        .first()
        .fill(details.code);
    });
});