Extract CableCar responses code to a concern

app/controllers/concerns/cablecar_responses.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+module CablecarResponses
+  extend ActiveSupport::Concern
+
+  included do
+    include CableReady::Broadcaster
+  end
+
+  private
+
+  def partial(path, options = {})
+    { html: render_to_string(partial: path, **options) }
+  end
+end

app/controllers/split_checkout_controller.rb

@@ -8,7 +8,7 @@ class SplitCheckoutController < ::BaseController
   include OrderStockCheck
   include Spree::BaseHelper
   include CheckoutCallbacks
-  include CableReady::Broadcaster
+  include CablecarResponses
 
   helper 'terms_and_conditions'
   helper 'checkout'
@@ -36,10 +36,6 @@ class SplitCheckoutController < ::BaseController
 
   private
 
-  def partial(path, options = {})
-    { html: render_to_string(partial: path, **options) }
-  end
-
   def clear_invalid_payments
     @order.payments.with_state(:invalid).delete_all
   end