Remove code duplication and test PDF creation

app/controllers/spree/admin/orders_controller_decorator.rb

@@ -37,9 +37,7 @@ Spree::Admin::OrdersController.class_eval do
   end
 
   def invoice
-    pdf = render_to_string pdf: "invoice-#{@order.number}.pdf",
-                           template: invoice_template,
-                           formats: [:html], encoding: "UTF-8"
+    pdf = InvoiceRenderer.new.render(@order)
 
     Spree::OrderMailer.invoice_email(@order.id, pdf).deliver
     flash[:success] = t('admin.orders.invoice_email_sent')
@@ -48,7 +46,7 @@ Spree::Admin::OrdersController.class_eval do
   end
 
   def print
-    render pdf: "invoice-#{@order.number}", template: invoice_template, encoding: "UTF-8"
+    render InvoiceRenderer.new.args(@order)
   end
 
   def print_ticket
@@ -61,10 +59,6 @@ Spree::Admin::OrdersController.class_eval do
 
   private
 
-  def invoice_template
-    Spree::Config.invoice_style2? ? "spree/admin/orders/invoice2" : "spree/admin/orders/invoice"
-  end
-
   def require_distributor_abn
     unless @order.distributor.abn.present?
       flash[:error] = t(:must_have_valid_business_number, enterprise_name: @order.distributor.name)

app/services/bulk_invoice_service.rb

@@ -1,5 +1,4 @@
 class BulkInvoiceService
-  include WickedPdf::PdfHelper
   attr_reader :id
 
   def initialize
@@ -11,10 +10,7 @@ class BulkInvoiceService
     orders = Spree::Order.where(id: order_ids)
 
     orders.each do |order|
-      invoice = renderer.render_to_string pdf: "invoice-#{order.number}.pdf",
-                                          template: invoice_template,
-                                          formats: [:html], encoding: "UTF-8",
-                                          locals: { :@order => order }
+      invoice = InvoiceRenderer.new.render_to_string(order)
 
       pdf << CombinePDF.parse(invoice)
     end
@@ -41,14 +37,6 @@ class BulkInvoiceService
     'tmp/invoices'
   end
 
-  def renderer
-    ApplicationController.new
-  end
-
-  def invoice_template
-    Spree::Config.invoice_style2? ? "spree/admin/orders/invoice2" : "spree/admin/orders/invoice"
-  end
-
   def file_directory
     Dir.mkdir(directory) unless File.exist?(directory)
     directory

app/services/invoice_renderer.rb

@@ -0,0 +1,29 @@
+class InvoiceRenderer
+  def render_to_string(order)
+    renderer.render_to_string(args(order))
+  end
+
+  def args(order)
+    {
+      pdf: "invoice-#{order.number}.pdf",
+      template: invoice_template,
+      formats: [:html],
+      encoding: "UTF-8",
+      locals: { :@order => order }
+    }
+  end
+
+  private
+
+  def renderer
+    ApplicationController.new
+  end
+
+  def invoice_template
+    if Spree::Config.invoice_style2?
+      "spree/admin/orders/invoice2"
+    else
+      "spree/admin/orders/invoice"
+    end
+  end
+end

spec/services/invoice_renderer_spec.rb

@@ -0,0 +1,15 @@
+require 'spec_helper'
+
+describe InvoiceRenderer do
+  let(:service) { described_class.new }
+
+  it "creates a PDF invoice" do
+    order = create(:completed_order_with_fees)
+    order.bill_address = order.ship_address
+    order.save!
+
+    result = service.render_to_string(order)
+
+    expect(result).to match /^%PDF/
+  end
+end