Refactor OrderUpdater to decorate Spree's one

This replaces the nasty class eval and provides some encapsulation

app/models/order_updater.rb

@@ -0,0 +1,41 @@
+require 'delegate'
+
+class OrderUpdater < SimpleDelegator
+  # TODO: This logic adapted from Spree 2.4, remove when we get there
+  # Handles state updating in a much more logical way than < 2.4
+  # Specifically, doesn't depend on payments.last to determine payment state
+  # Also swapped: == 0 for .zero?, .size == 0 for empty? and .size > 0 for !empty?
+  # See:
+  # https://github.com/spree/spree/commit/38b8456183d11fc1e00e395e7c9154c76ef65b85
+  # https://github.com/spree/spree/commit/7b264acff7824f5b3dc6651c106631d8f30b147a
+  def update_payment_state
+    last_state = order.payment_state
+    if payments.present? && payments.valid.empty?
+      order.payment_state = 'failed'
+    elsif order.state == 'canceled' && order.payment_total.zero?
+      order.payment_state = 'void'
+    else
+      # This part added so that we don't need to override order.outstanding_balance
+      balance = order.outstanding_balance
+      balance = -1 * order.payment_total if canceled_and_paid_for?
+      order.payment_state = 'balance_due' if balance > 0
+      order.payment_state = 'credit_owed' if balance < 0
+      order.payment_state = 'paid' if balance.zero?
+
+      # Original logic
+      # order.payment_state = 'balance_due' if order.outstanding_balance > 0
+      # order.payment_state = 'credit_owed' if order.outstanding_balance < 0
+      # order.payment_state = 'paid' if !order.outstanding_balance?
+    end
+    order.state_changed('payment') if last_state != order.payment_state
+    order.payment_state
+  end
+
+  private
+
+  # Taken from order.outstanding_balance in Spree 2.4
+  # See: https://github.com/spree/spree/commit/7b264acff7824f5b3dc6651c106631d8f30b147a
+  def canceled_and_paid_for?
+    order.canceled? && order.payments.present? && !order.payments.completed.empty?
+  end
+end

app/models/spree/order_updater_decorator.rb

@@ -1,41 +0,0 @@
-module Spree
-  OrderUpdater.class_eval do
-    # TODO: This logic adapted from Spree 2.4, remove when we get there
-    # Handles state updating in a much more logical way than < 2.4
-    # Specifically, doesn't depend on payments.last to determine payment state
-    # Also swapped: == 0 for .zero?, .size == 0 for empty? and .size > 0 for !empty?
-    # See:
-    # https://github.com/spree/spree/commit/38b8456183d11fc1e00e395e7c9154c76ef65b85
-    # https://github.com/spree/spree/commit/7b264acff7824f5b3dc6651c106631d8f30b147a
-    def update_payment_state
-      last_state = order.payment_state
-      if payments.present? && payments.valid.empty?
-        order.payment_state = 'failed'
-      elsif order.state == 'canceled' && order.payment_total.zero?
-        order.payment_state = 'void'
-      else
-        # This part added so that we don't need to override order.outstanding_balance
-        balance = order.outstanding_balance
-        balance = -1 * order.payment_total if canceled_and_paid_for?
-        order.payment_state = 'balance_due' if balance > 0
-        order.payment_state = 'credit_owed' if balance < 0
-        order.payment_state = 'paid' if balance.zero?
-
-        # Original logic
-        # order.payment_state = 'balance_due' if order.outstanding_balance > 0
-        # order.payment_state = 'credit_owed' if order.outstanding_balance < 0
-        # order.payment_state = 'paid' if !order.outstanding_balance?
-      end
-      order.state_changed('payment') if last_state != order.payment_state
-      order.payment_state
-    end
-
-    private
-
-    # Taken from order.outstanding_balance in Spree 2.4
-    # See: https://github.com/spree/spree/commit/7b264acff7824f5b3dc6651c106631d8f30b147a
-    def canceled_and_paid_for?
-      order.canceled? && order.payments.present? && !order.payments.completed.empty?
-    end
-  end
-end

spec/models/order_updater_spec.rb

@@ -1,9 +1,9 @@
 require 'spec_helper'
 
-describe Spree::OrderUpdater do
+describe OrderUpdater do
   context "#updating_payment_state" do
     let(:order) { build(:order) }
-    let(:order_updater) { described_class.new(order) }
+    let(:order_updater) { described_class.new(Spree::OrderUpdater.new(order)) }
 
     it "is failed if no valid payments" do
       allow(order).to receive_message_chain(:payments, :valid, :empty?) { true }