Change spree_countries.iso column to be unique

We're using `spree_countries.iso` as a primary key between prices and
countries. In order to add a foreign key constraint, primary keys have
to be unique. This adds the necessary uniqueness constraint.

A few tests had to be amended to not create the same country many times.

Author: mamhoff

core/app/models/spree/country.rb

@@ -16,7 +16,8 @@ class Country < Spree::Base
       dependent: :restrict_with_error,
       inverse_of: :country
 
-    validates :name, :iso_name, presence: true
+    validates :name, :iso_name, :iso, presence: true
+    validates :iso, uniqueness: true
 
     self.allowed_ransackable_attributes = %w[name]
 

core/db/migrate/20250628094037_change_countries_iso_to_unique.rb

@@ -0,0 +1,7 @@
+class ChangeCountriesIsoToUnique < ActiveRecord::Migration[8.0]
+  def change
+    remove_index :spree_countries, :iso
+
+    add_index :spree_countries, :iso, unique: true
+  end
+end

core/spec/helpers/base_helper_spec.rb

@@ -11,7 +11,9 @@
     let(:country) { create(:country) }
 
     before do
-      3.times { create(:country) }
+      create(:country, iso: "BR")
+      create(:country, iso: "DE")
+      create(:country, iso: "FR")
     end
 
     context "with no checkout zone defined" do
@@ -24,7 +26,7 @@
       end
 
       it "uses locales for country names" do
-        expect(available_countries).to include(having_attributes(name: "United States of America"))
+        expect(available_countries).to include(having_attributes(name: "Brazil"))
       end
     end
 

core/spec/lib/spree/core/importer/order_spec.rb

@@ -226,7 +226,7 @@ module Core
           }
         end
 
-        let(:other_state) { create(:state, name: "Uhuhuh", country: create(:country)) }
+        let(:other_state) { create(:state, name: "Uhuhuh", country: create(:country, iso: "BR")) }
 
         before do
           ship_address.delete(:state_id)

core/spec/models/spree/country_spec.rb

@@ -104,16 +104,15 @@
   end
 
   describe '#prices' do
-    let(:country) { create(:country) }
+    let(:country) { create(:country, iso: "BR") }
     subject { country.prices }
 
     it { is_expected.to be_a(ActiveRecord::Associations::CollectionProxy) }
 
     context "if the country has associated prices" do
-      let!(:price_one) { create(:price) }
-      let!(:price_two) { create(:price) }
+      let!(:price_one) { create(:price, country:) }
+      let!(:price_two) { create(:price, country:) }
       let!(:price_three) { create(:price) }
-      let(:country) { create(:country, prices: [price_one, price_two]) }
 
       it { is_expected.to contain_exactly(price_one, price_two) }
     end

core/spec/models/spree/credit_card_spec.rb

@@ -88,7 +88,7 @@ def self.payment_states
     end
 
     let!(:persisted_card) { Spree::CreditCard.find(credit_card.id) }
-    let(:country) { create(:country, states_required: true) }
+    let(:country) { create(:country, iso: "BR", states_required: true) }
     let(:state) { create(:state, country:) }
     let(:valid_address_attributes) do
       {

core/spec/models/spree/price_spec.rb

@@ -169,7 +169,7 @@
 
   describe 'scopes' do
     describe '.for_any_country' do
-      let(:country) { create(:country) }
+      let(:country) { create(:country, iso: "BR") }
       let!(:fallback_price) { create(:price, country_iso: nil) }
       let!(:country_price) { create(:price, country:) }
 

core/spec/models/spree/tax_rate_spec.rb

@@ -64,12 +64,14 @@
     end
 
     context "when no rate zones match the tax zone" do
-      let(:rate_zone) { create(:zone, :with_country) }
+      let(:usa) { create(:country) }
+      let(:rate_zone) { create(:zone, countries: [usa]) }
       let!(:rate) { create :tax_rate, zone: rate_zone }
 
       context "when there is no default tax zone" do
         context "and the zone has no shared members with the rate zone" do
-          let(:zone) { create(:zone, :with_country) }
+          let(:canada) { create(:country, iso: "CA")}
+          let(:zone) { create(:zone, countries: [canada]) }
 
           it "should return an empty array" do
             expect(subject).to eq([])
@@ -94,8 +96,8 @@
         end
 
         context "when the tax_zone is contained within a rate zone" do
-          let(:country1) { create :country }
-          let(:country2) { create :country }
+          let(:country1) { create :country, iso: "FR" }
+          let(:country2) { create :country, iso: "BR" }
           let(:rate_zone) { create(:zone, countries: [country1, country2]) }
           let(:zone) { create(:zone, countries: [country1]) }
 
@@ -127,7 +129,8 @@
         end
 
         context "when the zone is outside the default zone" do
-          let(:zone) { create(:zone, :with_country) }
+          let(:brazil) { create(:country, iso: "BR") }
+          let(:zone) { create(:zone, countries: [brazil]) }
 
           it { is_expected.to be_empty }
         end

core/spec/models/spree/zone_spec.rb

@@ -4,9 +4,11 @@
 
 RSpec.describe Spree::Zone, type: :model do
   describe 'for_address' do
-    let(:new_york_address) { create(:address, state_code: "NY") }
+    let(:canada) { create(:country, iso: "CA") }
+    let(:usa) { create(:country, iso: "US") }
+    let(:new_york_address) { create(:address, state_code: "NY", country: usa) }
     let(:alabama_address) { create(:address) }
-    let(:canada_address) { create(:address, country_iso_code: "CA") }
+    let(:canada_address) { create(:address, country: canada) }
 
     let!(:new_york_zone) { create(:zone, states: [new_york_address.state]) }
     let!(:alabama_zone) { create(:zone, states: [alabama_address.state]) }
@@ -101,7 +103,7 @@
       it "should remove existing state members" do
         zone = create(:zone, name: 'foo', zone_members: [])
         state = create(:state)
-        country = create(:country)
+        country = create(:country, iso: "BR")
         zone.members.create(zoneable: state)
         country_member = zone.members.create(zoneable: country)
         zone.save
@@ -159,8 +161,8 @@
 
   context ".with_shared_members" do
     let!(:country)  { create(:country) }
-    let!(:country2) { create(:country, name: 'OtherCountry') }
-    let!(:country3) { create(:country, name: 'TaxCountry') }
+    let!(:country2) { create(:country, iso: "MX", name: 'OtherCountry') }
+    let!(:country3) { create(:country, iso: "CA", name: 'TaxCountry') }
 
     subject(:zones_with_shared_members) { Spree::Zone.with_shared_members(zone) }