failing spec

failing_spec.rb

# app/models/credit_card.rb

class CreditCard < ActiveRecord::Base
  belongs_to :user

  ...

  def make_default!
    old = self.users.credit_cards.where(default: true).first

    puts old.default? # returns true

    unless old == self
      unless old.nil?
        old.default = false
        old.save
      end

      puts old.default? # returns false

      self.default = true
      self.save
    end
  end
end

# spec/models/credit_card_spec.rb

require 'spec_helper'

describe CreditCard do
  ... # shoulda matchers

  describe '#make_default!' do
    context 'with an existing default card' do
      let(:owner) { create :user }
      let(:existing_default) { create :credit_card, last_4: '9999', default: true, user: owner }
      let(:new_default) { create :credit_card, last_4: '1111', default: false, user: owner }

      before { new_default.make_default! }

      it 'sets a new default' do
        expect(new_default.default?).to be true
      end

      it 'sets the existing default to false' do
        expect(existing_default.default?).to be false# this is failing, returning true
      end
    end
  end
end