Ensure the URN is validated correctly

app/controllers/appointment_summaries_controller.rb

@@ -20,6 +20,9 @@ def create
 
   def download
     @appointment_summary = AppointmentSummary.new(appointment_summary_params)
+
+    return head :unprocessable_entity unless @appointment_summary.valid?
+
     output_document = OutputDocument.new(@appointment_summary, 'generic')
 
     send_data output_document.pdf,

app/models/appointment_summary.rb

@@ -18,7 +18,7 @@ def initialize(params = {})
   end
 
   validates :appointment_type, inclusion: { in: %w[standard 50_54] }
-  validates :urn, format: { with: /P[A-Z]{2}\d-\d[A-Z]{3}/ }, allow_blank: true
+  validates :urn, format: { with: /\AP[A-Z]{2}\d-\d[A-Z]{3}\z/ }, allow_blank: true
 
   def appointment_type
     @appointment_type

spec/models/appointment_summary_spec.rb

@@ -18,6 +18,9 @@
       it 'requires a valid form' do
         subject.urn = 'This would really suck if it were to get through!'
         expect(subject).to be_invalid
+
+        subject.urn = 'PMY9-0GCUwhoopsie'
+        expect(subject).to be_invalid
       end
     end
   end

spec/requests/downloading_a_pension_wise_digital_summary_spec.rb

@@ -0,0 +1,50 @@
+RSpec.describe 'Generating a Pension Wise Digital summary download', type: :request do
+  specify 'Successfully generating the download without a URN' do
+    post '/en/summary-document/download', params: {
+      appointment_summary: {
+        appointment_type: 'standard',
+        supplementary_benefits: true,
+        supplementary_debt: true,
+        supplementary_ill_health: true,
+        supplementary_defined_benefit_pensions: true,
+        supplementary_pension_transfers: true
+      }
+    }
+
+    expect(response.status).to eq(200)
+    expect(response.content_type).to eq('application/pdf')
+  end
+
+  specify 'Successfully generating the download with a valid URN' do
+    post '/en/summary-document/download', params: {
+      appointment_summary: {
+        urn: 'PMY9-0GCU',
+        appointment_type: 'standard',
+        supplementary_benefits: true,
+        supplementary_debt: true,
+        supplementary_ill_health: true,
+        supplementary_defined_benefit_pensions: true,
+        supplementary_pension_transfers: true
+      }
+    }
+
+    expect(response.status).to eq(200)
+    expect(response.content_type).to eq('application/pdf')
+  end
+
+  specify 'Attempting a download with an invalid URN' do
+    post '/en/summary-document/download', params: {
+      appointment_summary: {
+        urn: 'PMY9-0GCUwhoopsies',
+        appointment_type: 'standard',
+        supplementary_benefits: true,
+        supplementary_debt: true,
+        supplementary_ill_health: true,
+        supplementary_defined_benefit_pensions: true,
+        supplementary_pension_transfers: true
+      }
+    }
+
+    expect(response.status).to eq(422)
+  end
+end