Remove order association from inventory units

Inventory units link line items to shipments. Both of these have an
order. Let's make this a has_many association, through :shipments, which
are required.

This made a number of changes in the codebase necessary, such as
checking for order instead of order id identity.

core/app/models/spree/inventory_unit.rb

@@ -7,7 +7,6 @@ class InventoryUnit < Spree::Base
     CANCELABLE_STATES = ['on_hand', 'backordered', 'shipped']
 
     belongs_to :variant, -> { with_deleted }, class_name: "Spree::Variant", inverse_of: :inventory_units
-    belongs_to :order, class_name: "Spree::Order", inverse_of: :inventory_units
     belongs_to :shipment, class_name: "Spree::Shipment", touch: true, inverse_of: :inventory_units
     belongs_to :return_authorization, class_name: "Spree::ReturnAuthorization", inverse_of: :inventory_units
     belongs_to :carton, class_name: "Spree::Carton", inverse_of: :inventory_units
@@ -16,8 +15,9 @@ class InventoryUnit < Spree::Base
     has_many :return_items, inverse_of: :inventory_unit, dependent: :destroy
     has_one :original_return_item, class_name: "Spree::ReturnItem", foreign_key: :exchange_inventory_unit_id, dependent: :destroy
     has_one :unit_cancel, class_name: "Spree::UnitCancel"
+    has_one :order, through: :shipment
 
-    validates_presence_of :order, :shipment, :line_item, :variant
+    validates_presence_of :shipment, :line_item, :variant
 
     before_destroy :ensure_can_destroy
 

core/app/models/spree/order.rb

@@ -73,13 +73,16 @@ class CannotRebuildShipments < StandardError; end
     has_many :products, through: :variants
 
     # Shipping
-    has_many :inventory_units, inverse_of: :order
-    has_many :cartons, -> { distinct }, through: :inventory_units
     has_many :shipments, dependent: :destroy, inverse_of: :order do
       def states
         pluck(:state).uniq
       end
     end
+    has_many :inventory_units, through: :shipments
+    has_many :cartons, -> { distinct }, through: :inventory_units
+
+    has_many :order_stock_locations, class_name: "Spree::OrderStockLocation"
+    has_many :stock_locations, through: :order_stock_locations
 
     # Adjustments and promotions
     has_many :adjustments, -> { order(:created_at) }, as: :adjustable, inverse_of: :adjustable, dependent: :destroy

core/app/models/spree/order_cancellations.rb

@@ -25,7 +25,7 @@ def initialize(order)
   #
   # @return [Array<UnitCancel>] the units that have been canceled due to short shipping
   def short_ship(inventory_units, whodunnit:nil)
-    if inventory_units.map(&:order_id).uniq != [@order.id]
+    if inventory_units.map(&:order).uniq != [@order]
       raise ArgumentError, "Not all inventory units belong to this order"
     end
 

core/app/models/spree/reimbursement.rb

@@ -154,7 +154,7 @@ def generate_number
     end
 
     def validate_return_items_belong_to_same_order
-      if return_items.any? { |ri| ri.inventory_unit.order_id != order_id }
+      if return_items.any? { |ri| ri.inventory_unit.order != order }
         errors.add(:base, :return_items_order_id_does_not_match)
       end
     end

core/app/models/spree/shipment.rb

@@ -262,11 +262,10 @@ def determine_state(order)
       end
     end
 
-    def set_up_inventory(state, variant, order, line_item)
+    def set_up_inventory(state, variant, _order, line_item)
       inventory_units.create(
         state: state,
         variant_id: variant.id,
-        order_id: order.id,
         line_item_id: line_item.id
       )
     end

core/app/models/spree/shipping_manifest.rb

@@ -7,7 +7,7 @@ def initialize(inventory_units:)
 
   def for_order(order)
     Spree::ShippingManifest.new(
-      inventory_units: @inventory_units.select { |iu| iu.order_id == order.id }
+      inventory_units: @inventory_units.select { |iu| iu.shipment.order_id == order.id }
     )
   end
 

core/lib/spree/testing_support/factories/inventory_unit_factory.rb

@@ -6,10 +6,9 @@
 FactoryBot.define do
   factory :inventory_unit, class: 'Spree::InventoryUnit' do
     variant
-    order
-    line_item { build(:line_item, order: order, variant: variant) }
+    line_item { build(:line_item, variant: variant) }
     state 'on_hand'
-    shipment { build(:shipment, state: 'pending', order: order) }
+    shipment { build(:shipment, state: 'pending', order: line_item.order) }
     # return_authorization
   end
 end

core/lib/spree/testing_support/factories/shipment_factory.rb

@@ -25,7 +25,6 @@
       shipment.order.line_items.each do |line_item|
         line_item.quantity.times do
           shipment.inventory_units.create!(
-            order_id: shipment.order_id,
             variant_id: line_item.variant_id,
             line_item_id: line_item.id
           )

core/spec/models/spree/shipment_spec.rb

@@ -264,6 +264,7 @@
         end
 
         before do
+          allow(line_item).to receive(:order) { order }
           allow(shipment).to receive(:inventory_units) { inventory_units }
           allow(inventory_units).to receive_message_chain(:includes, :joins).and_return inventory_units
         end
@@ -650,7 +651,7 @@
     let(:inventory_units) { double }
 
     let(:params) do
-      { variant_id: variant.id, state: 'on_hand', order_id: order.id, line_item_id: line_item.id }
+      { variant_id: variant.id, state: 'on_hand', line_item_id: line_item.id }
     end
 
     before { allow(shipment).to receive_messages inventory_units: inventory_units }

core/spec/models/spree/shipping_manifest_spec.rb

@@ -9,8 +9,8 @@ module Spree
     let(:manifest) { described_class.new(inventory_units: inventory_units) }
 
     def build_unit(variant, attrs = {})
-      attrs = { order: order, variant: variant, shipment: shipment }.merge(attrs)
-      attrs[:line_item] = attrs[:order].contents.add(attrs[:variant])
+      attrs = { variant: variant, shipment: shipment }.merge(attrs)
+      attrs[:line_item] = order.contents.add(attrs[:variant])
       InventoryUnit.new(attrs)
     end
 
@@ -68,7 +68,7 @@ def build_unit(variant, attrs = {})
     end
 
     describe "#for_order" do
-      let!(:order2) { Order.create! }
+      let!(:order2) { create(:order_with_line_items) }
       context 'single unit' do
         let(:inventory_units) { [build_unit(variant)] }
         it "has single ManifestItem in correct order" do
@@ -81,7 +81,7 @@ def build_unit(variant, attrs = {})
       end
 
       context 'one units in each order' do
-        let(:inventory_units) { [build_unit(variant), build_unit(variant, order: order2)] }
+        let(:inventory_units) { [build_unit(variant), build_unit(variant, shipment: order2.shipments.first)] }
         it "has single ManifestItem in first order" do
           expect(manifest.for_order(order).items.count).to eq 1
         end