Make cart taxes configurable via Spree::Store object

CHANGELOG.md

@@ -1,5 +1,20 @@
 ## Solidus 1.3.0 (unreleased)
 
+*   Taxes for carts now configurable via the `Spree::Store` object
+
+    In VAT countries, carts (orders without addresses) have to be shown with
+    adjustments for the country whose taxes the cart's prices supposedly include.
+    This might differ from `Spree::Store` to `Spree::Store`. We're introducting
+    the `cart_tax_country_iso` setting on Spree::Store for this purpose.
+
+    Previously the setting for what country any prices include
+    Spree::Zone.default_tax. That, however, would *also* implicitly tag all
+    prices in Spree as including the taxes from that zone. Introducing the cart
+    tax setting on Spree::Store relieves that boolean of some of its
+    responsibilities.
+
+    https://github.com/solidusio/solidus/pull/933
+
 *   Make Spree::Product#prices association return all prices
 
     Previously, only non-master variant prices would have been returned here.

api/spec/controllers/spree/api/line_items_controller_spec.rb

@@ -119,7 +119,7 @@ module Spree
 
       context "order contents changed after shipments were created" do
         let!(:store) { create(:store) }
-        let!(:order) { Order.create }
+        let!(:order) { Order.create(store: store) }
         let!(:line_item) { order.contents.add(product.master) }
 
         before { order.create_proposed_shipments }

core/app/models/spree/app_configuration.rb

@@ -126,6 +126,12 @@ class AppConfiguration < Preferences::Configuration
     #   @return [String] Two-letter ISO code of a {Spree::Country} to assumed as the country of an unidentified customer (default: "US")
     preference :default_country_iso, :string, default: 'US'
 
+    # @!attribute [rw] admin_vat_country_iso
+    #   Set this if you want to enter prices in the backend including value added tax.
+    #   @return [String, nil] Two-letter ISO code of that {Spree::Country} for which
+    #      prices are entered in the backend (default: nil)
+    preference :admin_vat_country_iso, :string, default: nil
+
     # @!attribute [rw] expedited_exchanges
     #   Kicks off an exchange shipment upon return authorization save.
     #   charge customer if they do not return items within timely manner.
@@ -324,6 +330,19 @@ def stock
       @stock_configuration ||= Spree::Core::StockConfiguration.new
     end
 
+    # Default admin VAT location
+    #
+    # An object that responds to :state_id and :country_id so it can double as a Spree::Address in
+    # Spree::Zone.for_address. Takes the `admin_vat_country_iso` as input.
+    #
+    # @see admin_vat_country_iso The admin VAT country
+    # @return [Spree::Tax::TaxLocation] default tax location
+    def admin_vat_location
+      @default_tax_location ||= Spree::Tax::TaxLocation.new(
+        country: Spree::Country.find_by(iso: admin_vat_country_iso)
+      )
+    end
+
     # all the following can be deprecated when store prefs are no longer supported
     # @private
     DEPRECATED_STORE_PREFERENCES = {

core/app/models/spree/order.rb

@@ -215,7 +215,11 @@ def tax_zone
 
     # Returns the address for taxation based on configuration
     def tax_address
-      Spree::Config[:tax_using_ship_address] ? ship_address : bill_address
+      if Spree::Config[:tax_using_ship_address]
+        ship_address
+      else
+        bill_address
+      end || store.default_cart_tax_location
     end
 
     def updater

core/app/models/spree/store.rb

@@ -23,6 +23,11 @@ def self.default
       where(default: true).first || new
     end
 
+    def default_cart_tax_location
+      @default_cart_tax_location ||=
+        Spree::Tax::TaxLocation.new(country: Spree::Country.find_by(iso: cart_tax_country_iso))
+    end
+
     private
 
     def ensure_default_exists_and_is_unique

core/app/models/spree/tax/tax_location.rb

@@ -0,0 +1,33 @@
+module Spree
+  module Tax
+    # A class exclusively used as a drop-in replacement for a default tax address.
+    # It responds to `:country_id` and `:state_id`.
+    #
+    # @attr_reader [Integer] country_id the ID of a Spree::Country object
+    # @attr_reader [Integer] state_id the ID of a Spree::State object
+    class TaxLocation
+      attr_reader :country_id, :state_id
+
+      # Create a new TaxLocation object
+      #
+      # @see Spree::Zone.for_address
+      #
+      # @param [Spree::Country] country a Spree::Country object, default: nil
+      # @param [Spree::State] state a Spree::State object, default: nil
+      #
+      # @return [Spree::Tax::TaxLocation] a Spree::Tax::TaxLocation object
+      def initialize(country: nil, state: nil)
+        @country_id = country && country.id
+        @state_id = state && state.id
+      end
+
+      def ==(other)
+        state_id == other.state_id && country_id == other.country_id
+      end
+
+      def empty?
+        country_id.nil? && state_id.nil?
+      end
+    end
+  end
+end

core/app/models/spree/tax_rate.rb

@@ -27,6 +27,9 @@ class TaxRate < Spree::Base
     validates :tax_category_id, presence: true
     validates_with DefaultTaxZoneValidator
 
+    # Finds all tax rates whose zones match a given address
+    scope :for_address, ->(address) { joins(:zone).merge(Spree::Zone.for_address(address)) }
+
     # Finds geographically matching tax rates for a tax zone.
     # We do not know if they are/aren't applicable until we attempt to apply these rates to
     # the items contained within the Order itself.

core/db/default/spree/stores.rb

@@ -5,5 +5,6 @@
     s.name              = 'Spree Demo Site'
     s.url               = 'demo.spreecommerce.com'
     s.mail_from_address = '[email protected]'
+    s.cart_tax_country_iso = Spree::Config.admin_vat_location
   end.save!
 end

core/db/migrate/20160229133259_add_cart_tax_country_iso_to_spree_store.rb

@@ -0,0 +1,5 @@
+class AddCartTaxCountryIsoToSpreeStore < ActiveRecord::Migration
+  def change
+    add_column :spree_stores, :cart_tax_country_iso, :string, null: true, default: nil
+  end
+end

core/spec/models/spree/app_configuration_spec.rb

@@ -30,4 +30,16 @@
       expect(prefs[:default_country_iso]).to eq("US")
     end
   end
+
+  describe '@admin_vat_country_iso' do
+    it 'is `nil` by default' do
+      expect(prefs[:admin_vat_country_iso]).to eq(nil)
+    end
+  end
+
+  it 'has a default admin VAT location with nil values by default' do
+    expect(prefs.admin_vat_location).to eq(Spree::Tax::TaxLocation.new)
+    expect(prefs.admin_vat_location.state_id).to eq(nil)
+    expect(prefs.admin_vat_location.country_id).to eq(nil)
+  end
 end

core/spec/models/spree/order/totals_spec.rb

@@ -2,7 +2,7 @@
 
 module Spree
   describe Order, type: :model do
-    let(:order) { Order.create }
+    let(:order) { create(:order) }
     let(:shirt) { create(:variant) }
 
     context "adds item to cart and activates promo" do

core/spec/models/spree/order_merger_spec.rb

@@ -4,6 +4,7 @@
 module Spree
   describe OrderMerger, type: :model do
     let(:variant) { create(:variant) }
+    let!(:store) { create(:store, default: true) }
     let(:order_1) { Spree::Order.create }
     let(:order_2) { Spree::Order.create }
     let(:user) { stub_model(Spree::LegacyUser, email: "[email protected]") }

core/spec/models/spree/order_spec.rb

@@ -395,22 +395,51 @@ def merge!(other_order, user = nil)
   end
 
   describe "#tax_address" do
+    let(:order) { build(:order, ship_address: ship_address, bill_address: bill_address, store: store) }
+    let(:store) { build(:store) }
+
     before { Spree::Config[:tax_using_ship_address] = tax_using_ship_address }
     subject { order.tax_address }
 
-    context "when tax_using_ship_address is true" do
-      let(:tax_using_ship_address) { true }
+    context "when the order has no addresses" do
+      let(:ship_address) { nil }
+      let(:bill_address) { nil }
+
+      context "when tax_using_ship_address is true" do
+        let(:tax_using_ship_address) { true }
 
-      it 'returns ship_address' do
-        expect(subject).to eq(order.ship_address)
+        it 'returns the stores default cart tax location' do
+          expect(subject).to eq(store.default_cart_tax_location)
+        end
+      end
+
+      context "when tax_using_ship_address is not true" do
+        let(:tax_using_ship_address) { false }
+
+        it 'returns the stores default cart tax location' do
+          expect(subject).to eq(store.default_cart_tax_location)
+        end
       end
     end
 
-    context "when tax_using_ship_address is not true" do
-      let(:tax_using_ship_address) { false }
+    context "when the order has addresses" do
+      let(:ship_address) { build(:address) }
+      let(:bill_address) { build(:address) }
 
-      it "returns bill_address" do
-        expect(subject).to eq(order.bill_address)
+      context "when tax_using_ship_address is true" do
+        let(:tax_using_ship_address) { true }
+
+        it 'returns ship_address' do
+          expect(subject).to eq(order.ship_address)
+        end
+      end
+
+      context "when tax_using_ship_address is not true" do
+        let(:tax_using_ship_address) { false }
+
+        it "returns bill_address" do
+          expect(subject).to eq(order.bill_address)
+        end
       end
     end
   end

core/spec/models/spree/store_spec.rb

@@ -1,6 +1,8 @@
 require 'spec_helper'
 
 describe Spree::Store, type: :model do
+  it { is_expected.to respond_to(:cart_tax_country_iso) }
+
   describe ".by_url" do
     let!(:store)    { create(:store, url: "website1.com\nwww.subdomain.com") }
     let!(:store_2)  { create(:store, url: 'freethewhales.com') }
@@ -50,4 +52,23 @@
       expect(store.default).not_to be true
     end
   end
+
+  describe '#default_cart_tax_location' do
+    subject { described_class.new(cart_tax_country_iso: cart_tax_country_iso) }
+    context "when there is no cart_tax_country_iso set" do
+      let(:cart_tax_country_iso) { '' }
+      it "responds with an empty default_cart_tax_location" do
+        expect(subject.default_cart_tax_location).to be_empty
+      end
+    end
+
+    context "when there is a cart_tax_country_iso set" do
+      let(:country) { create(:country, iso: "DE") }
+      let(:cart_tax_country_iso) { country.iso }
+
+      it "responds with a default_cart_tax_location with that country" do
+        expect(subject.default_cart_tax_location).to eq(Spree::Tax::TaxLocation.new(country: country))
+      end
+    end
+  end
 end

core/spec/models/spree/tax/tax_location_spec.rb

@@ -0,0 +1,68 @@
+require 'spec_helper'
+
+RSpec.describe Spree::Tax::TaxLocation do
+  let(:country) { build_stubbed(:country) }
+  let(:state) { build_stubbed(:state) }
+
+  subject { described_class.new }
+
+  it { is_expected.to respond_to(:state_id) }
+  it { is_expected.to respond_to(:country_id) }
+
+  describe "default values" do
+    it "has a nil state and country id" do
+      expect(subject.state_id).to eq(nil)
+      expect(subject.country_id).to eq(nil)
+    end
+  end
+
+  describe '#==' do
+    let(:other) { described_class.new(state: nil, country: nil) }
+
+    it 'compares the values of state id and country id and does not care about object identity' do
+      expect(subject).to eq(other)
+    end
+  end
+
+  describe "initialization" do
+    subject { described_class.new(args) }
+
+    context 'with a country object' do
+      let(:args) { { country: country } }
+
+      it "will yield a location with that country's id" do
+        expect(subject.country_id).to eq(country.id)
+      end
+    end
+
+    context 'with a state object' do
+      let(:args) { { state: state } }
+
+      it "will yield a location with that state's id" do
+        expect(subject.state_id).to eq(state.id)
+      end
+    end
+  end
+
+  describe "#empty?" do
+    subject { described_class.new(args).empty? }
+
+    context 'with a country present' do
+      let(:args) { { country: country } }
+
+      it { is_expected.to be false }
+    end
+
+    context 'with a state present' do
+      let(:args) { { state: state } }
+
+      it { is_expected.to be false }
+    end
+
+    context 'with no region data present' do
+      let(:args) { {} }
+
+      it { is_expected.to be true }
+    end
+  end
+end

core/spec/models/spree/tax_rate_spec.rb

@@ -1,6 +1,53 @@
 require 'spec_helper'
 
 describe Spree::TaxRate, type: :model do
+  context '.for_address' do
+    let(:germany) { create(:country, iso: "DE") }
+    let(:germany_zone) { create(:zone, countries: [germany]) }
+    let!(:german_tax) { create(:tax_rate, zone: germany_zone) }
+    let(:france) { create(:country, iso: "FR") }
+    let(:france_zone) { create(:zone, countries: [france]) }
+    let!(:french_tax) { create(:tax_rate, zone: france_zone) }
+    let(:eu_zone) { create(:zone, countries: [germany, france]) }
+    let!(:eu_tax) { create(:tax_rate, zone: eu_zone) }
+    let(:usa) { create(:country, iso: "US") }
+    let(:us_zone) { create(:zone, countries: [usa]) }
+    let!(:us_tax) { create(:tax_rate, zone: us_zone) }
+    let(:new_york) { create(:state, country: usa, state_code: "NY") }
+    let(:new_york_zone) { create(:zone, states: [new_york]) }
+    let!(:new_york_tax) { create(:tax_rate, zone: new_york_zone) }
+    let(:alabama) { create(:state, country: usa, state_code: "AL") }
+    let(:alabama_zone) { create(:zone, states: [alabama]) }
+    let!(:alabama_tax) { create(:tax_rate, zone: alabama_zone) }
+
+    subject(:rates_for_address) { Spree::TaxRate.for_address(address) }
+
+    context 'when address is in germany' do
+      let(:address) { create(:address, country_iso_code: "DE") }
+      it { is_expected.to contain_exactly(german_tax, eu_tax) }
+    end
+
+    context 'when address is in france' do
+      let(:address) { create(:address, country_iso_code: "FR") }
+      it { is_expected.to contain_exactly(french_tax, eu_tax) }
+    end
+
+    context 'when address is in new york' do
+      let(:address) { create(:address, country_iso_code: "US", state_code: "NY") }
+      it { is_expected.to contain_exactly(new_york_tax, us_tax) }
+    end
+
+    context 'when address is in alabama' do
+      let(:address) { create(:address, country_iso_code: "US", state_code: "AL") }
+      it { is_expected.to contain_exactly(alabama_tax, us_tax) }
+    end
+
+    context 'when address is in alaska' do
+      let(:address) { create(:address, country_iso_code: "US", state_code: "AK") }
+      it { is_expected.to contain_exactly(us_tax) }
+    end
+  end
+
   context ".for_zone" do
     subject(:rates_for_zone) { Spree::TaxRate.for_zone(zone) }