Use current order helper instead of instance variable

The API to get the current order in a controller is the helper, not the
instance variable.

Author: mamhoff

lib/decorators/frontend/controllers/solidus_subscriptions/spree/orders_controller/create_subscription_line_items.rb

@@ -24,7 +24,7 @@ def self.prepended(base)
         private
 
         def handle_subscription_line_items
-          line_item = @current_order.line_items.find_by(variant_id: params[:variant_id])
+          line_item = current_order.line_items.find_by(variant_id: params[:variant_id])
           create_subscription_line_item(line_item)
         end
       end

lib/generators/solidus_subscriptions/install/templates/app/controllers/concerns/create_subscription.rb

@@ -11,7 +11,7 @@ module CreateSubscription
   private
 
   def handle_subscription_line_items
-    line_item = @current_order.line_items.find_by(variant_id: params[:variant_id])
+    line_item = current_order.line_items.find_by(variant_id: params[:variant_id])
     create_subscription_line_item(line_item)
   end
 

spec/controllers/concerns/create_subscription_spec.rb

@@ -5,19 +5,14 @@
   subject(:controller_instance) do
     Class.new(ApplicationController) do
       include CreateSubscription
-      attr_accessor :params, :current_order
-
-      def initialize(params = {})
-        super
-      end
     end.new
   end
 
   let(:variant) { create(:variant) }
   let(:order) { create(:order) }
 
   before do
-    controller_instance.current_order = order
+    allow(controller_instance).to receive(:current_order).and_return(order)
   end
 
   describe '#subscription_line_item_params_present?' do
@@ -49,15 +44,19 @@ def initialize(params = {})
   end
 
   describe '#handle_subscription_line_items' do
-    context 'when subscription params are missing' do
-      it 'does not invoke handle_subscription_line_items and does not create a subscription line item' do
-        order.line_items.count
+    before do
+      allow(controller_instance).to receive(:params).and_return(params)
+    end
 
-        controller_instance.params = {
+    context 'when subscription params are missing' do
+      let(:params) do
+        {
           variant_id: variant.id,
           subscription_line_item: {}
         }
+      end
 
+      it 'does not invoke handle_subscription_line_items and does not create a subscription line item' do
         expect(controller_instance.send(:valid_subscription_line_item_params?)).to be false
 
         expect(controller_instance).not_to receive(:handle_subscription_line_items)
@@ -67,17 +66,19 @@ def initialize(params = {})
     end
 
     context 'when subscription params are present' do
-      it 'calls create_subscription_line_item with the correct line item' do
-        line_item = create(:line_item, order: order, variant: variant)
-
-        controller_instance.params = {
+      let(:params) do
+        {
           variant_id: variant.id,
           subscription_line_item: {
             subscribable_id: 1,
             quantity: 2,
             interval_length: 1
           }
         }
+      end
+
+      it 'calls create_subscription_line_item with the correct line item' do
+        line_item = create(:line_item, order: order, variant: variant)
 
         allow(order.line_items).to receive(:find_by).with(variant_id: variant.id).and_return(line_item)