Make checkout controller add flash error if order contains any type of error

Here we add translations for a particular case where the credit card expiry date is in the past

app/controllers/checkout_controller.rb

@@ -165,7 +165,7 @@ class CheckoutController < Spree::StoreController
       checkout_succeeded
       redirect_to(order_path(@order)) && return
     else
-      flash[:error] = order_workflow_error
+      flash[:error] = order_error
       checkout_failed
     end
   end
@@ -179,8 +179,6 @@ class CheckoutController < Spree::StoreController
       @order.select_shipping_method(shipping_method_id) if @order.state == "delivery"
 
       next if advance_order_state(@order)
-
-      flash[:error] = order_workflow_error
       return update_failed
     end
 
@@ -205,7 +203,7 @@ class CheckoutController < Spree::StoreController
     false
   end
 
-  def order_workflow_error
+  def order_error
     if @order.errors.present?
       @order.errors.full_messages.to_sentence
     else
@@ -245,6 +243,7 @@ class CheckoutController < Spree::StoreController
   end
 
   def update_failed
+    flash[:error] = order_error if flash.empty?
     checkout_failed
     update_failed_response
   end

config/locales/en.yml

@@ -40,6 +40,8 @@ en:
         shipping_category_id: "Shipping Category"
         variant_unit: "Variant Unit"
         variant_unit_name: "Variant Unit Name"
+      spree/credit_card:
+        base: "Credit Card"
       order_cycle:
         orders_close_at: Close date
     errors:
@@ -50,6 +52,10 @@ en:
               taken: "There's already an account for this email. Please login or reset your password."
         spree/order:
           no_card: There are no authorised credit cards available to charge
+        spree/credit_card:
+          attributes:
+            base:
+              card_expired: "has expired"
         order_cycle:
           attributes:
             orders_close_at:

spec/controllers/checkout_controller_spec.rb

@@ -197,13 +197,13 @@ describe CheckoutController, type: :controller do
       allow(controller).to receive(:current_order).and_return(order)
     end
 
-    it "returns errors" do
+    it "returns errors and flash if order.update_attributes fails" do
       spree_post :update, format: :json, order: {}
       expect(response.status).to eq(400)
-      expect(response.body).to eq({ errors: assigns[:order].errors, flash: {} }.to_json)
+      expect(response.body).to eq({ errors: assigns[:order].errors, flash: { error: order.errors.full_messages.to_sentence } }.to_json)
     end
 
-    it "returns flash" do
+    it "returns errors and flash if order.next fails" do
       allow(order).to receive(:update_attributes).and_return true
       allow(order).to receive(:next).and_return false
       spree_post :update, format: :json, order: {}