Abstraction Of payments layer

abstraction_layer.rb

# config/environments/{test,development,production}.rb
config.stripe_key = "foobar"

Rails.configuration.stripe_key


# Controller
Purchase.charge("tok_jOq0M8vJprCUUU")


# Model
class Purchase < AR::Base

  def self.charge(gateway, card)
    gateway = PaymentGateway.new(amount, currency, token, description)
    gateway.charge!
  rescue PaymentGateway::PaymentFailed => e
    self.errors[:base] << "Payment failed"
  end

end

# Payment Gateway
class PaymentGateway < Struct.new(amount, currency, card, description)
  class PaymentFailed < StandardError; end
  
  def charge!
    Stripe::Charge.create(
      :amount => price,
      :currency => "usd",
      :card => card, # obtained with Stripe.js
      :description => "Charge for awesome shit"
    )
  end
  
end


# Test
describe PaymentGateway do
  
  describe "when charging cc" do
    
    describe "with valid params" do
      ...
    end
    
    describe "with invalid params" do
      ...
    end
    
    describe "raising exceptions" do
      ...
    end
    
  end
  
end