Fill in a Stripe Elements (https://stripe.com/docs/elements) credit card field using capybara

capybara_fill_stripe_elements.rb

def fill_stripe_elements(card: '4242424242424242', expiry: '1234', cvc: '123', postal: '12345')
  using_wait_time(10) { 
    frame = find('#card-element > div > iframe')
    within_frame(frame) do
    card.to_s.chars.each do |piece|
      find_field('cardnumber').send_keys(piece)
    end

    find_field('exp-date').send_keys expiry
    find_field('cvc').send_keys cvc
    find_field('postal').send_keys postal
  end }
end