Add Zone.for_address scope

core/app/models/spree/zone.rb

@@ -26,6 +26,7 @@ class Zone < Spree::Base
               country_ids
             ).uniq
           end
+    scope :for_address, ->(address) { with_member_ids(address.try(:state_id), address.try(:country_id)) }
 
     alias :members :zone_members
     accepts_nested_attributes_for :zone_members, allow_destroy: true, reject_if: proc { |a| a['zoneable_id'].blank? }

core/spec/models/spree/zone_spec.rb

@@ -1,6 +1,50 @@
 require 'spec_helper'
 
 describe Spree::Zone, type: :model do
+  describe 'for_address' do
+    let(:new_york_address) { create(:address, state_code: "NY") }
+    let(:alabama_address) { create(:address) }
+    let(:canada_address) { create(:address, country_iso_code: "CA") }
+
+    let!(:new_york_zone) { create(:zone, states: [new_york_address.state]) }
+    let!(:alabama_zone) { create(:zone, states: [alabama_address.state]) }
+    let!(:united_states_zone) { create(:zone, countries: [new_york_address.country]) }
+    let!(:canada_zone) { create(:zone, countries: [canada_address.country]) }
+    let!(:north_america_zone) { create(:zone, countries: [canada_address.country, new_york_address.country]) }
+    subject { Spree::Zone.for_address(address) }
+
+    context 'when there is no address' do
+      let(:address) { nil }
+      it 'returns an empty relation' do
+        expect(subject).to eq([])
+      end
+    end
+
+    context 'for an address in New York' do
+      let(:address) { new_york_address }
+
+      it 'matches the New York zone' do
+        expect(subject).to include(new_york_zone)
+      end
+
+      it 'matches the United States zone' do
+        expect(subject).to include(united_states_zone)
+      end
+
+      it 'does not match the Alabama zone' do
+        expect(subject).not_to include(alabama_zone)
+      end
+
+      it 'does not match the Canadian zone' do
+        expect(subject).not_to include(canada_zone)
+      end
+
+      it 'matches the North America zone' do
+        expect(subject).to include(north_america_zone)
+      end
+    end
+  end
+
   context "#match" do
     let(:country_zone) { create(:zone, name: 'CountryZone') }
     let(:country) do