diff --git a/app/models/spree/payment.rb b/app/models/spree/payment.rb
new file mode 100644
index 0000000000..ccda57105c
--- /dev/null
+++ b/app/models/spree/payment.rb
@@ -0,0 +1,158 @@
+module Spree
+  class Payment < ActiveRecord::Base
+    include Spree::Payment::Processing
+
+    IDENTIFIER_CHARS = (('A'..'Z').to_a + ('0'..'9').to_a - %w(0 1 I O)).freeze
+
+    belongs_to :order, class_name: 'Spree::Order'
+    belongs_to :source, polymorphic: true
+    belongs_to :payment_method, class_name: 'Spree::PaymentMethod'
+
+    has_many :offsets, -> { where("source_type = 'Spree::Payment' AND amount < 0 AND state = 'completed'") },
+      class_name: "Spree::Payment", foreign_key: :source_id
+    has_many :log_entries, as: :source
+
+    before_validation :validate_source
+    before_save :set_unique_identifier
+
+    after_save :create_payment_profile, if: :profiles_supported?
+
+    # update the order totals, etc.
+    after_save :update_order
+    # invalidate previously entered payments
+    after_create :invalidate_old_payments
+
+    attr_accessor :source_attributes
+    after_initialize :build_source
+
+    scope :from_credit_card, -> { where(source_type: 'Spree::CreditCard') }
+    scope :with_state, ->(s) { where(state: s.to_s) }
+    scope :completed, -> { with_state('completed') }
+    scope :pending, -> { with_state('pending') }
+    scope :failed, -> { with_state('failed') }
+    scope :valid, -> { where('state NOT IN (?)', %w(failed invalid)) }
+
+    after_rollback :persist_invalid
+
+    def persist_invalid
+      return unless ['failed', 'invalid'].include?(state)
+      state_will_change!
+      save 
+    end
+
+    # order state machine (see http://github.com/pluginaweek/state_machine/tree/master for details)
+    state_machine initial: :checkout do
+      # With card payments, happens before purchase or authorization happens
+      event :started_processing do
+        transition from: [:checkout, :pending, :completed, :processing], to: :processing
+      end
+      # When processing during checkout fails
+      event :failure do
+        transition from: [:pending, :processing], to: :failed
+      end
+      # With card payments this represents authorizing the payment
+      event :pend do
+        transition from: [:checkout, :processing], to: :pending
+      end
+      # With card payments this represents completing a purchase or capture transaction
+      event :complete do
+        transition from: [:processing, :pending, :checkout], to: :completed
+      end
+      event :void do
+        transition from: [:pending, :completed, :checkout], to: :void
+      end
+      # when the card brand isnt supported
+      event :invalidate do
+        transition from: [:checkout], to: :invalid
+      end
+    end
+
+    def currency
+      order.currency
+    end
+
+    def money
+      Spree::Money.new(amount, { currency: currency })
+    end
+    alias display_amount money
+
+    def offsets_total
+      offsets.pluck(:amount).sum
+    end
+
+    def credit_allowed
+      amount - offsets_total
+    end
+
+    def can_credit?
+      credit_allowed > 0
+    end
+
+    # see https://github.com/spree/spree/issues/981
+    def build_source
+      return if source_attributes.nil?
+      if payment_method and payment_method.payment_source_class
+        self.source = payment_method.payment_source_class.new(source_attributes)
+      end
+    end
+
+    def actions
+      return [] unless payment_source and payment_source.respond_to? :actions
+      payment_source.actions.select { |action| !payment_source.respond_to?("can_#{action}?") or payment_source.send("can_#{action}?", self) }
+    end
+
+    def payment_source
+      res = source.is_a?(Payment) ? source.source : source
+      res || payment_method
+    end
+
+    private
+
+    def validate_source
+      if source && !source.valid?
+        source.errors.each do |field, error|
+          field_name = I18n.t("activerecord.attributes.#{source.class.to_s.underscore}.#{field}")
+          self.errors.add(Spree.t(source.class.to_s.demodulize.underscore), "#{field_name} #{error}")
+        end
+      end
+      return !errors.present?
+    end
+
+    def profiles_supported?
+      payment_method.respond_to?(:payment_profiles_supported?) && payment_method.payment_profiles_supported?
+    end
+
+    def create_payment_profile
+      return unless source.is_a?(CreditCard) && source.number && !source.has_payment_profile?
+      payment_method.create_profile(self)
+    rescue ActiveMerchant::ConnectionError => e
+      gateway_error e
+    end
+
+    def invalidate_old_payments
+      order.payments.with_state('checkout').where("id != ?", self.id).each do |payment|
+        payment.invalidate!
+      end
+    end
+
+    def update_order
+      order.payments.reload
+      order.update!
+    end
+
+    # Necessary because some payment gateways will refuse payments with
+    # duplicate IDs. We *were* using the Order number, but that's set once and
+    # is unchanging. What we need is a unique identifier on a per-payment basis,
+    # and this is it. Related to #1998.
+    # See https://github.com/spree/spree/issues/1998#issuecomment-12869105
+    def set_unique_identifier
+      begin
+        self.identifier = generate_identifier
+      end while self.class.exists?(identifier: self.identifier)
+    end
+
+    def generate_identifier
+      Array.new(8){ IDENTIFIER_CHARS.sample }.join
+    end
+  end
+end
diff --git a/app/models/spree/payment/processing.rb b/app/models/spree/payment/processing.rb
new file mode 100644
index 0000000000..98e2cf4c1e
--- /dev/null
+++ b/app/models/spree/payment/processing.rb
@@ -0,0 +1,210 @@
+module Spree
+  class Payment < ActiveRecord::Base
+    module Processing
+      def process!
+        if payment_method && payment_method.source_required?
+          if source
+            if !processing?
+              if payment_method.supports?(source)
+                if payment_method.auto_capture?
+                  purchase!
+                else
+                  authorize!
+                end
+              else
+                invalidate!
+                raise Core::GatewayError.new(Spree.t(:payment_method_not_supported))
+              end
+            end
+          else
+            raise Core::GatewayError.new(Spree.t(:payment_processing_failed))
+          end
+        end
+      end
+
+      def authorize!
+        started_processing!
+        gateway_action(source, :authorize, :pend)
+      end
+
+      def purchase!
+        started_processing!
+        gateway_action(source, :purchase, :complete)
+      end
+
+      def capture!
+        return true if completed?
+        started_processing!
+        protect_from_connection_error do
+          check_environment
+
+          if payment_method.payment_profiles_supported?
+            # Gateways supporting payment profiles will need access to credit card object because this stores the payment profile information
+            # so supply the authorization itself as well as the credit card, rather than just the authorization code
+            response = payment_method.capture(self, source, gateway_options)
+          else
+            # Standard ActiveMerchant capture usage
+            response = payment_method.capture(money.money.cents,
+                                              response_code,
+                                              gateway_options)
+          end
+
+          handle_response(response, :complete, :failure)
+        end
+      end
+
+      def void_transaction!
+        return true if void?
+        protect_from_connection_error do
+          check_environment
+
+          if payment_method.payment_profiles_supported?
+            # Gateways supporting payment profiles will need access to credit card object because this stores the payment profile information
+            # so supply the authorization itself as well as the credit card, rather than just the authorization code
+            response = payment_method.void(self.response_code, source, gateway_options)
+          else
+            # Standard ActiveMerchant void usage
+            response = payment_method.void(self.response_code, gateway_options)
+          end
+          record_response(response)
+
+          if response.success?
+            self.response_code = response.authorization
+            self.void
+          else
+            gateway_error(response)
+          end
+        end
+      end
+
+      def credit!(credit_amount=nil)
+        protect_from_connection_error do
+          check_environment
+
+          credit_amount ||= credit_allowed >= order.outstanding_balance.abs ? order.outstanding_balance.abs : credit_allowed.abs
+          credit_amount = credit_amount.to_f
+
+          if payment_method.payment_profiles_supported?
+            response = payment_method.credit((credit_amount * 100).round, source, response_code, gateway_options)
+          else
+            response = payment_method.credit((credit_amount * 100).round, response_code, gateway_options)
+          end
+
+          record_response(response)
+
+          if response.success?
+            self.class.create(
+              :order => order,
+              :source => self,
+              :payment_method => payment_method,
+              :amount => credit_amount.abs * -1,
+              :response_code => response.authorization,
+              :state => 'completed'
+            )
+          else
+            gateway_error(response)
+          end
+        end
+      end
+
+      def partial_credit(amount)
+        return if amount > credit_allowed
+        started_processing!
+        credit!(amount)
+      end
+
+      def gateway_options
+        options = { :email    => order.email,
+                    :customer => order.email,
+                    :ip       => order.last_ip_address,
+                    # Need to pass in a unique identifier here to make some
+                    # payment gateways happy.
+                    #
+                    # For more information, please see Spree::Payment#set_unique_identifier
+                    :order_id => gateway_order_id }
+
+        options.merge!({ :shipping => order.ship_total * 100,
+                         :tax      => order.tax_total * 100,
+                         :subtotal => order.item_total * 100,
+                         :discount => order.promo_total * 100,
+                         :currency => currency })
+
+        options.merge!({ :billing_address  => order.bill_address.try(:active_merchant_hash),
+                        :shipping_address => order.ship_address.try(:active_merchant_hash) })
+
+        options
+      end
+
+      private
+
+      def gateway_action(source, action, success_state)
+        protect_from_connection_error do
+          check_environment
+
+          response = payment_method.send(action, (amount * 100).round,
+                                         source,
+                                         gateway_options)
+          handle_response(response, success_state, :failure)
+        end
+      end
+
+      def handle_response(response, success_state, failure_state)
+        record_response(response)
+
+        if response.success?
+          unless response.authorization.nil?
+            self.response_code = response.authorization
+            self.avs_response = response.avs_result['code']
+
+            if response.cvv_result
+              self.cvv_response_code = response.cvv_result['code']
+              self.cvv_response_message = response.cvv_result['message']
+            end
+          end
+          self.send("#{success_state}!")
+        else
+          self.send(failure_state)
+          gateway_error(response)
+        end
+      end
+
+      def record_response(response)
+        log_entries.create(:details => response.to_yaml)
+      end
+
+      def protect_from_connection_error
+        begin
+          yield
+        rescue ActiveMerchant::ConnectionError => e
+          gateway_error(e)
+        end
+      end
+
+      def gateway_error(error)
+        if error.is_a? ActiveMerchant::Billing::Response
+          text = error.params['message'] || error.params['response_reason_text'] || error.message
+        elsif error.is_a? ActiveMerchant::ConnectionError
+          text = Spree.t(:unable_to_connect_to_gateway)
+        else
+          text = error.to_s
+        end
+        logger.error(Spree.t(:gateway_error))
+        logger.error("  #{error.to_yaml}")
+        raise Core::GatewayError.new(text)
+      end
+
+      # Saftey check to make sure we're not accidentally performing operations on a live gateway.
+      # Ex. When testing in staging environment with a copy of production data.
+      def check_environment
+        return if payment_method.environment == Rails.env
+        message = Spree.t(:gateway_config_unavailable) + " - #{Rails.env}"
+        raise Core::GatewayError.new(message)
+      end
+
+      # The unique identifier to be passed in to the payment gateway
+      def gateway_order_id
+        "#{order.number}-#{self.identifier}"
+      end
+    end
+  end
+end
diff --git a/spec/factories.rb b/spec/factories.rb
index ad3c804c92..327565ea1b 100644
--- a/spec/factories.rb
+++ b/spec/factories.rb
@@ -15,6 +15,22 @@ require 'spree/testing_support/factories'
 #   * order_with_inventory_unit_shipped
 #   * completed_order_with_totals
 #
+
+# allows credit card info to be saved to the database which is needed for factories to work properly
+class TestCard < Spree::CreditCard
+  def remove_readonly_attributes(attributes) attributes; end
+end
+
+FactoryBot.define do
+  factory :credit_card, class: TestCard do
+    verification_value 123
+    month 12
+    year { Time.now.year + 1 }
+    number '4111111111111111'
+    cc_type 'visa'
+  end
+end
+
 FactoryBot.define do
   factory :classification, class: Spree::Classification do
   end
diff --git a/spec/models/spree/payment_original_spec.rb b/spec/models/spree/payment_original_spec.rb
new file mode 100644
index 0000000000..8f28ac14dd
--- /dev/null
+++ b/spec/models/spree/payment_original_spec.rb
@@ -0,0 +1,639 @@
+require 'spec_helper'
+
+describe Spree::Payment do
+  let(:order) do
+    order = Spree::Order.new(:bill_address => Spree::Address.new,
+                             :ship_address => Spree::Address.new)
+  end
+
+  let(:gateway) do
+    gateway = Spree::Gateway::Bogus.new(:environment => 'test', :active => true)
+    gateway.stub :source_required => true
+    gateway
+  end
+
+  let(:card) do
+    mock_model(Spree::CreditCard, :number => "4111111111111111",
+                                  :has_payment_profile? => true)
+  end
+
+  let(:payment) do
+    payment = Spree::Payment.new
+    payment.source = card
+    payment.order = order
+    payment.payment_method = gateway
+    payment
+  end
+
+  let(:amount_in_cents) { payment.amount.to_f * 100 }
+
+  let!(:success_response) do
+    double('success_response', :success? => true,
+           :authorization => '123',
+           :avs_result => { 'code' => 'avs-code' },
+           :cvv_result => { 'code' => 'cvv-code', 'message' => "CVV Result"})
+  end
+
+  let(:failed_response) { double('gateway_response', :success? => false) }
+
+  before(:each) do
+    # So it doesn't create log entries every time a processing method is called
+    payment.log_entries.stub(:create)
+  end
+
+  context 'validations' do
+    it "returns useful error messages when source is invalid" do
+      payment.source = Spree::CreditCard.new
+      payment.should_not be_valid
+      cc_errors = payment.errors['Credit Card']
+      cc_errors.should include("Number can't be blank")
+      cc_errors.should include("Month is not a number")
+      cc_errors.should include("Year is not a number")
+      cc_errors.should include("Verification Value can't be blank")
+    end
+  end
+
+  # Regression test for https://github.com/spree/spree/pull/2224
+  context 'failure' do
+
+    it 'should transition to failed from pending state' do
+      payment.state = 'pending'
+      payment.failure
+      payment.state.should eql('failed')
+    end
+
+    it 'should transition to failed from processing state' do
+      payment.state = 'processing'
+      payment.failure
+      payment.state.should eql('failed')
+    end
+
+  end
+
+  context 'invalidate' do
+    it 'should transition from checkout to invalid' do
+      payment.state = 'checkout'
+      payment.invalidate
+      payment.state.should eq('invalid')
+    end
+  end
+
+  context "processing" do
+    before do
+      payment.stub(:update_order)
+      payment.stub(:create_payment_profile)
+    end
+
+    context "#process!" do
+      it "should purchase if with auto_capture" do
+        payment.payment_method.should_receive(:auto_capture?).and_return(true)
+        payment.should_receive(:purchase!)
+        payment.process!
+      end
+
+      it "should authorize without auto_capture" do
+        payment.payment_method.should_receive(:auto_capture?).and_return(false)
+        payment.should_receive(:authorize!)
+        payment.process!
+      end
+
+      it "should make the state 'processing'" do
+        payment.should_receive(:started_processing!)
+        payment.process!
+      end
+
+      it "should invalidate if payment method doesnt support source" do
+        payment.payment_method.should_receive(:supports?).with(payment.source).and_return(false)
+        expect { payment.process!}.to raise_error(Spree::Core::GatewayError)
+        payment.state.should eq('invalid')
+      end
+
+    end
+
+    context "#authorize" do
+      it "should call authorize on the gateway with the payment amount" do
+        payment.payment_method.should_receive(:authorize).with(amount_in_cents,
+                                                               card,
+                                                               anything).and_return(success_response)
+        payment.authorize!
+      end
+
+      it "should call authorize on the gateway with the currency code" do
+        payment.stub :currency => 'GBP'
+        payment.payment_method.should_receive(:authorize).with(amount_in_cents,
+                                                               card,
+                                                               hash_including({:currency => "GBP"})).and_return(success_response)
+        payment.authorize!
+      end
+
+      it "should log the response" do
+        payment.log_entries.should_receive(:create).with(:details => anything)
+        payment.authorize!
+      end
+
+      context "when gateway does not match the environment" do
+        it "should raise an exception" do
+          gateway.stub :environment => "foo"
+          expect { payment.authorize! }.to raise_error(Spree::Core::GatewayError)
+        end
+      end
+
+      context "if successful" do
+        before do
+          payment.payment_method.should_receive(:authorize).with(amount_in_cents,
+                                                                 card,
+                                                                 anything).and_return(success_response)
+        end
+
+        it "should store the response_code, avs_response and cvv_response fields" do
+          payment.authorize!
+          payment.response_code.should == '123'
+          payment.avs_response.should == 'avs-code'
+          payment.cvv_response_code.should == 'cvv-code'
+          payment.cvv_response_message.should == 'CVV Result'
+        end
+
+        it "should make payment pending" do
+          payment.should_receive(:pend!)
+          payment.authorize!
+        end
+      end
+
+      context "if unsuccessful" do
+        it "should mark payment as failed" do
+          gateway.stub(:authorize).and_return(failed_response)
+          payment.should_receive(:failure)
+          payment.should_not_receive(:pend)
+          lambda {
+            payment.authorize!
+          }.should raise_error(Spree::Core::GatewayError)
+        end
+      end
+    end
+
+    context "purchase" do
+      it "should call purchase on the gateway with the payment amount" do
+        gateway.should_receive(:purchase).with(amount_in_cents, card, anything).and_return(success_response)
+        payment.purchase!
+      end
+
+      it "should log the response" do
+        payment.log_entries.should_receive(:create).with(:details => anything)
+        payment.purchase!
+      end
+
+      context "when gateway does not match the environment" do
+        it "should raise an exception" do
+          gateway.stub :environment => "foo"
+          expect { payment.purchase!  }.to raise_error(Spree::Core::GatewayError)
+        end
+      end
+
+      context "if successful" do
+        before do
+          payment.payment_method.should_receive(:purchase).with(amount_in_cents,
+                                                                card,
+                                                                anything).and_return(success_response)
+        end
+
+        it "should store the response_code and avs_response" do
+          payment.purchase!
+          payment.response_code.should == '123'
+          payment.avs_response.should == 'avs-code'
+        end
+
+        it "should make payment complete" do
+          payment.should_receive(:complete!)
+          payment.purchase!
+        end
+      end
+
+      context "if unsuccessful" do
+        it "should make payment failed" do
+          gateway.stub(:purchase).and_return(failed_response)
+          payment.should_receive(:failure)
+          payment.should_not_receive(:pend)
+          expect { payment.purchase! }.to raise_error(Spree::Core::GatewayError)
+        end
+      end
+    end
+
+    context "#capture" do
+      before do
+        payment.stub(:complete).and_return(true)
+      end
+
+      context "when payment is pending" do
+        before do
+          payment.state = 'pending'
+        end
+
+        context "if successful" do
+          before do
+            payment.payment_method.should_receive(:capture).with(payment, card, anything).and_return(success_response)
+          end
+
+          it "should make payment complete" do
+            payment.should_receive(:complete)
+            payment.capture!
+          end
+
+          it "should store the response_code" do
+            gateway.stub :capture => success_response
+            payment.capture!
+            payment.response_code.should == '123'
+          end
+        end
+
+        context "if unsuccessful" do
+          it "should not make payment complete" do
+            gateway.stub :capture => failed_response
+            payment.should_receive(:failure)
+            payment.should_not_receive(:complete)
+            expect { payment.capture! }.to raise_error(Spree::Core::GatewayError)
+          end
+        end
+      end
+
+      # Regression test for #2119
+      context "when payment is completed" do
+        before do
+          payment.state = 'completed'
+        end
+
+        it "should do nothing" do
+          payment.should_not_receive(:complete)
+          payment.payment_method.should_not_receive(:capture)
+          payment.log_entries.should_not_receive(:create)
+          payment.capture!
+        end
+      end
+    end
+
+    context "#void" do
+      before do
+        payment.response_code = '123'
+        payment.state = 'pending'
+      end
+
+      context "when profiles are supported" do
+        it "should call payment_gateway.void with the payment's response_code" do
+          gateway.stub :payment_profiles_supported? => true
+          gateway.should_receive(:void).with('123', card, anything).and_return(success_response)
+          payment.void_transaction!
+        end
+      end
+
+      context "when profiles are not supported" do
+        it "should call payment_gateway.void with the payment's response_code" do
+          gateway.stub :payment_profiles_supported? => false
+          gateway.should_receive(:void).with('123', anything).and_return(success_response)
+          payment.void_transaction!
+        end
+      end
+
+      it "should log the response" do
+        payment.log_entries.should_receive(:create).with(:details => anything)
+        payment.void_transaction!
+      end
+
+      context "when gateway does not match the environment" do
+        it "should raise an exception" do
+          gateway.stub :environment => "foo"
+          expect { payment.void_transaction! }.to raise_error(Spree::Core::GatewayError)
+        end
+      end
+
+      context "if successful" do
+        it "should update the response_code with the authorization from the gateway" do
+          # Change it to something different
+          payment.response_code = 'abc'
+          payment.void_transaction!
+          payment.response_code.should == '12345'
+        end
+      end
+
+      context "if unsuccessful" do
+        it "should not void the payment" do
+          gateway.stub :void => failed_response
+          payment.should_not_receive(:void)
+          expect { payment.void_transaction! }.to raise_error(Spree::Core::GatewayError)
+        end
+      end
+
+      # Regression test for #2119
+      context "if payment is already voided" do
+        before do
+          payment.state = 'void'
+        end
+
+        it "should not void the payment" do
+          payment.payment_method.should_not_receive(:void)
+          payment.void_transaction!
+        end
+      end
+    end
+
+    context "#credit" do
+      before do
+        payment.state = 'complete'
+        payment.response_code = '123'
+      end
+
+      context "when outstanding_balance is less than payment amount" do
+        before do
+          payment.order.stub :outstanding_balance => 10
+          payment.stub :credit_allowed => 1000
+        end
+
+        it "should call credit on the gateway with the credit amount and response_code" do
+          gateway.should_receive(:credit).with(1000, card, '123', anything).and_return(success_response)
+          payment.credit!
+        end
+      end
+
+      context "when outstanding_balance is equal to payment amount" do
+        before do
+          payment.order.stub :outstanding_balance => payment.amount
+        end
+
+        it "should call credit on the gateway with the credit amount and response_code" do
+          gateway.should_receive(:credit).with(amount_in_cents, card, '123', anything).and_return(success_response)
+          payment.credit!
+        end
+      end
+
+      context "when outstanding_balance is greater than payment amount" do
+        before do
+          payment.order.stub :outstanding_balance => 101
+        end
+
+        it "should call credit on the gateway with the original payment amount and response_code" do
+          gateway.should_receive(:credit).with(amount_in_cents.to_f, card, '123', anything).and_return(success_response)
+          payment.credit!
+        end
+      end
+
+      it "should log the response" do
+        payment.log_entries.should_receive(:create).with(:details => anything)
+        payment.credit!
+      end
+
+      context "when gateway does not match the environment" do
+        it "should raise an exception" do
+          gateway.stub :environment => "foo"
+          lambda { payment.credit! }.should raise_error(Spree::Core::GatewayError)
+        end
+      end
+
+      context "when response is successful" do
+        it "should create an offsetting payment" do
+          Spree::Payment.should_receive(:create)
+          payment.credit!
+        end
+
+        it "resulting payment should have correct values" do
+          payment.order.stub :outstanding_balance => 100
+          payment.stub :credit_allowed => 10
+
+          offsetting_payment = payment.credit!
+          offsetting_payment.amount.to_f.should == -10
+          offsetting_payment.should be_completed
+          offsetting_payment.response_code.should == '12345'
+          offsetting_payment.source.should == payment
+        end
+      end
+    end
+  end
+
+  context "when response is unsuccessful" do
+    it "should not create a payment" do
+      gateway.stub :credit => failed_response
+      Spree::Payment.should_not_receive(:create)
+      expect { payment.credit! }.to raise_error(Spree::Core::GatewayError)
+    end
+  end
+
+  context "when already processing" do
+    it "should return nil without trying to process the source" do
+      payment.state = 'processing'
+
+      payment.should_not_receive(:authorize!)
+      payment.should_not_receive(:purchase!)
+      payment.process!.should be_nil
+    end
+  end
+
+  context "with source required" do
+    context "raises an error if no source is specified" do
+      before do
+        payment.source = nil
+      end
+
+      specify do
+        expect { payment.process! }.to raise_error(Spree::Core::GatewayError, Spree.t(:payment_processing_failed))
+      end
+    end
+  end
+
+  context "with source optional" do
+    context "raises no error if source is not specified" do
+      before do
+        payment.source = nil
+        payment.payment_method.stub(:source_required? => false)
+      end
+
+      specify do
+        expect { payment.process! }.not_to raise_error
+      end
+    end
+  end
+
+  context "#credit_allowed" do
+    it "is the difference between offsets total and payment amount" do
+      payment.amount = 100
+      payment.stub(:offsets_total).and_return(0)
+      payment.credit_allowed.should == 100
+      payment.stub(:offsets_total).and_return(80)
+      payment.credit_allowed.should == 20
+    end
+  end
+
+  context "#can_credit?" do
+    it "is true if credit_allowed > 0" do
+      payment.stub(:credit_allowed).and_return(100)
+      payment.can_credit?.should be_true
+    end
+    it "is false if credit_allowed is 0" do
+      payment.stub(:credit_allowed).and_return(0)
+      payment.can_credit?.should be_false
+    end
+  end
+
+  context "#credit" do
+    context "when amount <= credit_allowed" do
+      it "makes the state processing" do
+        payment.state = 'completed'
+        payment.stub(:credit_allowed).and_return(10)
+        payment.partial_credit(10)
+        payment.should be_processing
+      end
+      it "calls credit on the source with the payment and amount" do
+        payment.state = 'completed'
+        payment.stub(:credit_allowed).and_return(10)
+        payment.should_receive(:credit!).with(10)
+        payment.partial_credit(10)
+      end
+    end
+    context "when amount > credit_allowed" do
+      it "should not call credit on the source" do
+        payment.state = 'completed'
+        payment.stub(:credit_allowed).and_return(10)
+        payment.partial_credit(20)
+        payment.should be_completed
+      end
+    end
+  end
+
+  context "#save" do
+    it "should call order#update!" do
+      payment = Spree::Payment.create(:amount => 100, :order => order)
+      order.should_receive(:update!)
+      payment.save
+    end
+
+    context "when profiles are supported" do
+      before do
+        gateway.stub :payment_profiles_supported? => true
+        payment.source.stub :has_payment_profile? => false
+      end
+
+
+      context "when there is an error connecting to the gateway" do
+        it "should call gateway_error " do
+          pending '[Spree build] Failing spec'
+          message = double("gateway_error")
+          connection_error = ActiveMerchant::ConnectionError.new(message, nil)
+          expect(gateway).to receive(:create_profile).and_raise(connection_error)
+          lambda do
+            Spree::Payment.create(
+              :amount => 100,
+              :order => order,
+              :source => card,
+              :payment_method => gateway
+            )
+          end.should raise_error(Spree::Core::GatewayError)
+        end
+      end
+
+      context "when successfully connecting to the gateway" do
+        it "should create a payment profile" do
+          payment.payment_method.should_receive :create_profile
+          payment = Spree::Payment.create(
+            :amount => 100,
+            :order => order,
+            :source => card,
+            :payment_method => gateway
+          )
+        end
+      end
+
+
+    end
+
+    context "when profiles are not supported" do
+      before { gateway.stub :payment_profiles_supported? => false }
+
+      it "should not create a payment profile" do
+        gateway.should_not_receive :create_profile
+        payment = Spree::Payment.create(
+          :amount => 100,
+          :order => order,
+          :source => card,
+          :payment_method => gateway
+        )
+      end
+    end
+  end
+
+  context "#build_source" do
+    it "should build the payment's source" do
+      params = { :amount => 100, :payment_method => gateway,
+                 :source_attributes => {
+        :expiry =>"1 / 99",
+        :number => '1234567890123',
+        :verification_value => '123'
+      }
+      }
+
+      payment = Spree::Payment.new(params)
+      payment.should be_valid
+      payment.source.should_not be_nil
+    end
+
+    it "errors when payment source not valid" do
+      params = { :amount => 100, :payment_method => gateway,
+                 :source_attributes => {:expiry => "1 / 12" }}
+
+      payment = Spree::Payment.new(params)
+      payment.should_not be_valid
+      payment.source.should_not be_nil
+      payment.source.should have(1).error_on(:number)
+      payment.source.should have(1).error_on(:verification_value)
+    end
+  end
+
+  context "#currency" do
+    before { order.stub(:currency) { "ABC" } }
+    it "returns the order currency" do
+      payment.currency.should == "ABC"
+    end
+  end
+
+  context "#display_amount" do
+    it "returns a Spree::Money for this amount" do
+      payment.display_amount.should == Spree::Money.new(payment.amount)
+    end
+  end
+
+  # Regression test for #2216
+  context "#gateway_options" do
+    before { order.stub(:last_ip_address => "192.168.1.1") }
+
+    it "contains an IP" do
+      payment.gateway_options[:ip].should == order.last_ip_address
+    end
+  end
+
+  context "#set_unique_identifier" do
+    # Regression test for #1998
+    it "sets a unique identifier on create" do
+      payment.run_callbacks(:save)
+      payment.identifier.should_not be_blank
+      payment.identifier.size.should == 8
+      payment.identifier.should be_a(String)
+    end
+
+    context "other payment exists" do
+      let(:other_payment) {
+        payment = Spree::Payment.new
+        payment.source = card
+        payment.order = order
+        payment.payment_method = gateway
+        payment
+      }
+
+      before { other_payment.save! }
+
+      it "doesn't set duplicate identifier" do
+        payment.should_receive(:generate_identifier).and_return(other_payment.identifier)
+        payment.should_receive(:generate_identifier).and_call_original
+
+        payment.run_callbacks(:save)
+
+        payment.identifier.should_not be_blank
+        payment.identifier.should_not == other_payment.identifier
+      end
+    end
+  end
+end