Add renewals column to boxi exemptions export (#904)

https://eaflood.atlassian.net/browse/RUBY-1978

app/models/reports/boxi/registration_exemptions_serializer.rb

@@ -3,7 +3,7 @@
 module Reports
   module Boxi
     class RegistrationExemptionsSerializer < BaseSerializer
-      ATTRIBUTES = WasteExemptionsEngine::RegistrationExemption.column_names
+      ATTRIBUTES = WasteExemptionsEngine::RegistrationExemption.column_names + ["renewal"]
 
       def file_name
         "registration_exemptions.csv"

app/models/waste_exemptions_engine/registration_exemption.rb

@@ -27,5 +27,11 @@ class RegistrationExemption < ::WasteExemptionsEngine::ApplicationRecord
         .includes(registration: :addresses)
         .order(:registered_on, :registration_id)
     }
+
+    # This is called "renewal" rather than "renewal?" so that it can behave
+    # like an attribute in the Boxi export service without any mapping logic.
+    def renewal
+      registration&.renewal?
+    end
   end
 end

spec/models/registration_exemption_spec.rb

@@ -57,4 +57,24 @@
       end
     end
   end
+
+  describe "#renewal" do
+    subject(:registration_exemption) { registration.registration_exemptions.first }
+
+    context "without a referring registration" do
+      let(:registration) { build(:registration) }
+
+      it "returns false" do
+        expect(subject.renewal).to be false
+      end
+    end
+
+    context "with a referring registration" do
+      let(:registration) { build(:registration, referring_registration: build(:registration)) }
+
+      it "returns true" do
+        expect(subject.renewal).to be true
+      end
+    end
+  end
 end

spec/models/reports/boxi/registration_exemptions_serializer_spec.rb

@@ -17,6 +17,7 @@ module Boxi
           result_lines = result.split("\n")
 
           expect(result_lines.first.split(",")).to include(*WasteExemptionsEngine::RegistrationExemption.column_names)
+          expect(result_lines.first.split(",")).to include("renewal")
           expect(result_lines.count).to eq(2)
         end