Add spec for new address scopes

spec/models/waste_carriers_engine/address_spec.rb

@@ -4,6 +4,28 @@
 
 module WasteCarriersEngine
   RSpec.describe Address do
+    describe 'scopes' do
+      let(:address_with_area) { create(:address, area: "Area Name") }
+      let(:address_without_area) { create(:address, area: "") }
+      let(:address_with_nil_area) { create(:address, area: nil) }
+      let(:address_with_postcode) { create(:address, postcode: "BS1 5AH") }
+      let(:address_without_postcode) { create(:address, postcode: nil) }
+
+      describe ".missing_area" do
+        it "returns addresses with an empty or nil area" do
+          expect(Address.missing_area).to include(address_without_area, address_with_nil_area)
+          expect(Address.missing_area).not_to include(address_with_area)
+        end
+      end
+
+      describe ".with_postcode" do
+        it "returns addresses with a postcode" do
+          expect(Address.with_postcode).to include(address_with_postcode)
+          expect(Address.with_postcode).not_to include(address_without_postcode)
+        end
+      end
+    end
+
     describe "#assign_house_number_and_address_lines" do
       let(:address) { build(:address) }