Add tests around invoice printing in PDF

- use PDF Reader to read pdf and get its content
 - check with we print the payment description information section with the right value

Gemfile

@@ -153,6 +153,7 @@ group :test do
   gem 'test-prof'
   gem 'webmock'
   gem 'rails-controller-testing'
+  gem 'pdf-reader'
   # See spec/spec_helper.rb for instructions
   # gem 'perftools.rb'
 end

Gemfile.lock

@@ -47,6 +47,7 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
+    Ascii85 (1.1.0)
     actioncable (5.2.6)
       actionpack (= 5.2.6)
       nio4r (~> 2.0)
@@ -113,6 +114,7 @@ GEM
       activerecord (>= 4.2)
     addressable (2.7.0)
       public_suffix (>= 2.0.2, < 5.0)
+    afm (0.2.2)
     andand (1.3.3)
     angular-rails-templates (1.1.0)
       railties (>= 4.2, < 7)
@@ -284,6 +286,7 @@ GEM
       temple (>= 0.8.0)
       tilt
     hashdiff (1.0.1)
+    hashery (2.1.2)
     highline (2.0.3)
     i18n (1.8.10)
       concurrent-ruby (~> 1.0)
@@ -384,6 +387,12 @@ GEM
       xml-simple
     paypal-sdk-merchant (1.117.2)
       paypal-sdk-core (~> 0.3.0)
+    pdf-reader (2.4.2)
+      Ascii85 (~> 1.0)
+      afm (~> 0.2.1)
+      hashery (~> 2.0)
+      ruby-rc4
+      ttfunk
     pg (1.2.3)
     power_assert (2.0.0)
     pry (0.13.1)
@@ -571,6 +580,7 @@ GEM
     thread_safe (0.3.6)
     tilt (2.0.10)
     timecop (0.9.4)
+    ttfunk (1.7.0)
     tzinfo (1.2.9)
       thread_safe (~> 0.1)
     uglifier (4.2.0)
@@ -694,6 +704,7 @@ DEPENDENCIES
   paperclip (~> 3.4.1)
   paranoia (~> 2.4)
   paypal-sdk-merchant (= 1.117.2)
+  pdf-reader
   pg (~> 1.2.3)
   pry
   pry-byebug

spec/features/admin/invoice_print_spec.rb

@@ -0,0 +1,103 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+feature '
+    As an administrator
+    I want to print a invoice as PDF
+', js: false do
+  include WebHelper
+  include AuthenticationHelper
+
+  let(:user) { create(:user) }
+  let(:product) { create(:simple_product) }
+  let(:distributor) { create(:distributor_enterprise, owner: user, charges_sales_tax: true) }
+  let(:order_cycle) do
+    create(:simple_order_cycle, name: 'One', distributors: [distributor],
+                                variants: [product.variants.first])
+  end
+
+  let(:order) do
+    create(:order_with_totals_and_distribution, user: user, distributor: distributor,
+                                                order_cycle: order_cycle, state: 'complete',
+                                                payment_state: 'balance_due')
+  end
+
+  describe "that contains right Payment Description at Checkout information" do
+    let!(:payment_method1) do
+      create(:stripe_sca_payment_method, distributors: [distributor], description: "description1")
+    end
+    let!(:payment_method2) do
+      create(:stripe_sca_payment_method, distributors: [distributor], description: "description2")
+    end
+
+    context "with no payment" do
+      it "do not display the payment description information" do
+        login_as_admin_and_visit spree.print_admin_order_path(order)
+        convert_pdf_to_page
+        expect(page).to have_no_content 'Payment Description at Checkout'
+      end
+    end
+
+    context "with one payment" do
+      let!(:payment1) do
+        create(:payment, order: order, state: 'completed', payment_method: payment_method1)
+      end
+      before do
+        order.save!
+      end
+
+      it "display the payment description section" do
+        login_as_admin_and_visit spree.print_admin_order_path(order)
+        convert_pdf_to_page
+        expect(page).to have_content 'Payment Description at Checkout'
+        expect(page).to have_content 'description1'
+      end
+    end
+
+    context "with two payments, and one that failed" do
+      before do
+        order.update payments: []
+        order.payments << create(:payment, order: order, state: 'completed',
+                                           payment_method: payment_method1, created_at: 1.day.ago)
+        order.payments << create(:payment, order: order, state: 'failed',
+                                           payment_method: payment_method2, created_at: 2.days.ago)
+        order.save!
+      end
+
+      it "display the payment description section and use the one from the completed payment" do
+        login_as_admin_and_visit spree.print_admin_order_path(order)
+        convert_pdf_to_page
+        expect(page).to have_content 'Payment Description at Checkout'
+        expect(page).to have_content 'description1'
+      end
+    end
+
+    context "with two completed payments" do
+      before do
+        order.update payments: []
+        order.payments << create(:payment, order: order, state: 'completed',
+                                           payment_method: payment_method1, created_at: 2.days.ago)
+        order.payments << create(:payment, order: order, state: 'completed',
+                                           payment_method: payment_method2, created_at: 1.day.ago)
+        order.save!
+      end
+
+      it "display the payment description section and use the one from the last payment" do
+        login_as_admin_and_visit spree.print_admin_order_path(order)
+        convert_pdf_to_page
+        expect(page).to have_content 'Payment Description at Checkout'
+        expect(page).to have_content 'description2'
+      end
+    end
+  end
+end
+
+def convert_pdf_to_page
+  temp_pdf = Tempfile.new('pdf')
+  temp_pdf << page.source.force_encoding('UTF-8')
+  reader = PDF::Reader.new(temp_pdf)
+  pdf_text = reader.pages.map(&:text)
+  temp_pdf.close
+  page.driver.response.instance_variable_set('@body', pdf_text)
+end