Hooking up active record model with external api in rails app

In my rails application, I have 2 different types of active record user, for e.g. User1 has first_name, email etc and User2 also has these attributes but for user 2 we get the data from an external API, so when creating the invoices I am passing the user model to the invoice, and I am thinking of doing something like this for User2

class User2
  def first_name
    if persisted?
      data('firstName')
    end
  end

  def email
    if persisted?
      data('email')
    end
  end

  private
  def data
    @__data ||= ExternalUserInfo.new(external_id).call
  end
end

The ExternalUserInfo client will make the call to the external API and return the response as such

{
  firstName: "John", email: "john@example.com"
}

The problem with this approach is that whenever I will need to write a spec which needs to create this user, then I will need to wrap that test around VCR cassette or stub the external request. So I wanted to review what could be a potential solution to avoid this or if this design even make sense at all