Ensure vaccination record returns variants

This ensures that if the vaccination record has disease types, then the
correct variable is returned for MMR or MMRV.

Jira-Issue: MAV-2821

Author: thomasleese

app/models/concerns/belongs_to_programme.rb

@@ -22,11 +22,13 @@ module BelongsToProgramme
   end
 
   def programme
-    find_options = {}
-    find_options[:disease_types] = disease_types if respond_to?(:disease_types)
-    find_options[:patient] = patient if respond_to?(:patient)
+    if (type = programme_type)
+      options = {}
+      options[:disease_types] = disease_types if respond_to?(:disease_types)
+      options[:patient] = patient if respond_to?(:patient)
 
-    Programme.find(programme_type, **find_options)
+      Programme.find(type, **options)
+    end
   end
 
   def programme=(value)

spec/models/vaccination_record_spec.rb

@@ -162,6 +162,34 @@
     end
   end
 
+  describe "#programme" do
+    subject { vaccination_record.programme }
+
+    before { Flipper.enable(:mmrv) }
+
+    context "for an MMRV vaccine" do
+      let(:programme) { Programme.mmr }
+      let(:vaccine) { Vaccine.find_by!(brand: "ProQuad") }
+
+      let(:vaccination_record) do
+        create(:vaccination_record, programme:, vaccine:)
+      end
+
+      its(:name) { should eq("MMRV") }
+    end
+
+    context "for an MMRV vaccination record without a vaccine" do
+      let(:programme) { Programme.mmr }
+      let(:disease_types) { %w[measles mumps rubella varicella] }
+
+      let(:vaccination_record) do
+        create(:vaccination_record, programme:, disease_types:, vaccine: nil)
+      end
+
+      its(:name) { should eq("MMRV") }
+    end
+  end
+
   describe "#dose_volume_ml" do
     subject { vaccination_record.dose_volume_ml }