Fake Stripe mock backend server for generating tokens for stripe.js

fake_stripe_server.rb

#!/usr/bin/env ruby
require 'sinatra/base'
require 'json'
require 'stripe_mock'

# Mount fake Sinatra Stripe Server to Capybara
#
# Example:
#
#   feature 'Subscribe' do
#     given!(:user) { create(:user) }
#     background { StripeMock.start }
#     after { StripeMock.stop }
#     scenario 'obtain stripe credit card token', :js do
#       server = FakeStripeServer.boot
#       Stripe.api_base = 'http://' + [server.host, server.port].join(':')
#       visit subscription_path(user.subscription)
#       ...
#     end
#
# or you can run the server manually form command line:
#
#   $ ./fake_stripe_server
#
# http://robots.thoughtbot.com/using-capybara-to-test-javascript-that-makes-http
# https://github.com/rebelidealist/stripe-ruby-mock/issues/52
class FakeStripeServer < Sinatra::Base

  def self.boot
    instance = new
    Capybara::Server.new(instance).tap { |server| server.boot }
  end

  get '/' do
    '<center>' <<
    '<h1>Hello, Fake $tripe Server here ☺</h1>' <<
    '<p><a href="/v1/tokens?card[number]=4242+4242+4242+4242&card[cvc]=123&card[exp_month]=7&card[exp_year]=2021&key=pk_test_3Bd9i4KBm6XZgEw3mjCjbC7K&payment_user_agent=stripe.js%2F0c86740&callback=sjsonp1413830642863&_method=POST">GET /v1/tokens</a></p>' <<
    '</center>'
  end

  # POST https://api.stripe.com/v1/tokens?card[number]=4242+4242+4242+4242&card[cvc]=123&card[exp_month]=7&card[exp_year]=2021&key=pk_test_3Bd9i4KBm6XZgEw3mjCjbC7K&payment_user_agent=stripe.js%2F0c86740&callback=sjsonp1413830642863&_method=POST
  post '/v1/tokens' do
    mock_response
  end

  # for debug use only
  # GET https://api.stripe.com/v1/tokens?card[number]=4242+4242+4242+4242&card[cvc]=123&card[exp_month]=7&card[exp_year]=2021&key=pk_test_3Bd9i4KBm6XZgEw3mjCjbC7K&payment_user_agent=stripe.js%2F0c86740&callback=sjsonp1413830642863&_method=POST
  get '/v1/tokens' do
    mock_response
  end

  def mock_response
    jsonp_callback = params[:callback]
    token = StripeMock.generate_card_token(params[:card])
    response_code = 200
    response = {
      id: token, # 'tok_4zkgf83otVadp0',
      livemode: false,
      created: Time.new.to_i,
      used: false,
      object: 'token',
      type: 'card',
      card: {
        id: 'card_4zkgMqNbIykebF',
        object: 'card',
        last4: params[:card][:number][-4..-1] || params[:card][:number],
        brand: 'Visa',
        funding: 'credit',
        exp_month: params[:card][:exp_month],
        exp_year: params[:card][:exp_year],
        fingerprint: 'TyO4SWrYg4hk0xNe',
        country: 'US',
        name: nil,
        address_line1: nil,
        address_line2: nil,
        address_city: nil,
        address_state: nil,
        address_zip: nil,
        address_country: nil,
        dynamic_last4: nil,
        customer: nil,
        type: 'Visa'
      }
    }
    "#{jsonp_callback}(#{JSON.generate(response)}, #{response_code})"
  end
end

### MAIN ####

if File.identical?(__FILE__, $0)
  StripeMock.start
  FakeStripeServer.run!
  StripeMock.stop
end

fake_stripe_specs.rb

require 'spec_helper'

feature 'User subscription' do
  before(:all) do
    server = FakeStripeServer.boot
    Stripe.api_base = 'http://' + [server.host, server.port].join(':')
  end

  before do
    StripeMock.start
    #StripeMock.toggle_debug(true)
    @stripe = StripeMock.create_test_helper
    @stripe.create_plan(id: 'basic')
    @stripe.create_plan(id: 'standard')
  end

  after do
    StripeMock.stop
  end
  
  background do
    sign_in_with(user.username, 'password')
    visit subscription_path
  end
  
  scenario 'upgrade from Free plan to Basic plan', :js do
    # ...
  end

end

subscription.html.erb

<% content_for :head do %>
  <% if Rails.env.test? %>
    <!-- https://js.stripe.com/v2/stripe-debug.js stored locally -->
    <%= render 'shared/stripe_debug_js_v2' %>
    <script type="text/javascript" charset="utf-8">
      $(document).ready(function() { Stripe.endpoint = "<%= Stripe.api_base + '/v1' %>"; });
    </script>
  <% else %>
    <script type="text/javascript" src="https://js.stripe.com/v2/"></script>
  <% end %>
<% end %>