Merge pull request bitzesty#166 from bitzesty/GA4

add GA4 conformance rule

app/validators/geographical_area_validator.rb

@@ -7,10 +7,17 @@ class GeographicalAreaValidator < TradeTariffBackend::Validator
   validation :GA2, 'The start date must be less than or equal to the end date.' do
     validates :validity_dates
   end
+
+  validation :GA4, 'The referenced parent geographical area group must be an existing geographical area with area code = 1 (geographical area group)', on: [:create, :update] do |record|
+    parent_sid = record.parent_geographical_area_group_sid
+    if parent_sid.present?
+      parent = record.class[geographical_area_sid: parent_sid]
+      parent.try(:geographical_code).to_s == "1"
+    end
+  end
 end
 
 # TODO: GA3
-# TODO: GA4
 # TODO: GA5
 # TODO: GA6
 # TODO: GA7

spec/models/geographical_area_spec.rb

@@ -137,5 +137,36 @@
     it { should validate_uniqueness.of([:geographical_area_id, :validity_start_date])}
     # GA2 The start date must be less than or equal to the end date.
     it { should validate_validity_dates }
+
+    describe "GA4" do
+      let(:geographical_area) {
+        build(:geographical_area, parent_geographical_area_group_sid: parent_id)
+      }
+
+      before { geographical_area.conformant? }
+
+      context "invalid parent id" do
+        let(:parent_id) { "435" }
+        it {
+          expect(geographical_area.conformance_errors).to have_key(:GA4)
+        }
+      end
+
+      context "invalid area code" do
+        let(:parent_id) {
+          create(:geographical_area, :country).geographical_area_sid
+        }
+        it {
+          expect(geographical_area.conformance_errors).to have_key(:GA4)
+        }
+      end
+
+      context "valid" do
+        let(:parent_id) {
+          create(:geographical_area, geographical_code: "1").geographical_area_sid
+        }
+        it { expect(geographical_area.conformance_errors).to be_empty }
+      end
+    end
   end
 end