Make update shipment handler accept inventory units

In
a1c78bb,
we updated the shipment serializer to push inventory units, so if we are
updating, we should use them as well in case there is a variant mismatch
as there is with exchanges

If a shipment happens to be created using the add_shipment_handler
instead of pushed with the serializer, even though that builds inventory
units from the line items matching the shipment items skus, we should
still be ok because it should match the inventory units similarly to how
it previously matched line items.

Change update shipment handler to expect flattened inventory items, since that is what is generated in the serializer

Make sure to cast quantity to an integer

Handle multiple inventory units of the same sku and quantity in update shipment handler

Fixes #39

lib/spree/wombat/handler/update_shipment_handler.rb

@@ -51,7 +51,7 @@ def process
           shipment_attributes["address_attributes"] = address_attributes if address_attributes
 
           missing_variants = []
-          missing_line_items = []
+          missing_inventory_units = []
 
           shipping_items = shipment_hsh.delete(:items)
           if shipping_items
@@ -65,24 +65,31 @@ def process
                 next
               end
 
-              line_item_id = shipment.order.line_items.where(variant_id: variant.id).pluck(:id).first
-              unless line_item_id
-                missing_line_items << sku
+              inventory_unit_id = shipment.inventory_units.where(variant_id: variant.id).pluck(:id).first
+              unless inventory_unit_id
+                missing_inventory_units << sku
                 next
               end
             end
 
             # check on items sku and quantity
-            shipment_lines = shipment.line_items.map { |li| {sku: li.variant.sku, quantity: li.quantity} }
-            received_shipping_items = shipping_items.map { |item| {sku: item[:product_id], quantity: item[:quantity]} }
+            shipment_lines = shipment.inventory_units.map do |inventory_unit|
+              quantity = inventory_unit.respond_to?(:quantity) ? inventory_unit.quantity : 1
+              { sku: inventory_unit.variant.sku, quantity: quantity }
+            end
+
+            received_shipping_items = shipping_items.map { |item| {sku: item[:product_id], quantity: item[:quantity].to_i} }
 
-            shipping_items_diff = received_shipping_items - shipment_lines
+            shipping_items_diff = received_shipping_items.reject do |item|
+              # using Array#delete deletes all of the instances of the item, we just want to delete the first
+              index_of_item = shipment_lines.index(item)
+              index_of_item && shipment_lines.delete_at(index_of_item)
+            end
 
             return response("The received shipment items do not match with the shipment, diff: #{shipping_items_diff}", 500) unless shipping_items_diff.empty?
 
             return response("Can't find variants with the following skus: #{missing_variants.join(', ')}", 500) unless missing_variants.empty?
-            return response("Can't find line_items with the following skus: #{missing_line_items.join(', ')} in the order.", 500) unless missing_line_items.empty?
-
+            return response("Can't find inventory_units with the following skus: #{missing_inventory_units.join(', ')} in the order.", 500) unless missing_inventory_units.empty?
           end
 
           # check if a state transition is required, and search for correct event to fire

spec/lib/spree/wombat/handler/update_shipment_handler_spec.rb

@@ -36,8 +36,8 @@ module Wombat
           context "with mismatching items in shipment" do
 
             before do
-              line_item.quantity = 2
-              line_item.save
+              original_item = message['shipment']['items'].first
+              message['shipment']['items'] << original_item
             end
 
             it "will return an error message with the mismatch diff" do
@@ -47,6 +47,22 @@ module Wombat
             end
           end
 
+          context "with multiple of the same items in a shipment" do
+            before do
+              new_inventory_unit = shipment.inventory_units.last.dup
+              new_inventory_unit.save!
+              original_item = message['shipment']['items'].first
+              message['shipment']['items'] << original_item
+            end
+
+            it "will return a proper message" do
+              responder = handler.process
+              expect(responder.summary).to eql "Updated shipment #{shipment.number}"
+              expect(responder.code).to eql 200
+            end
+
+          end
+
           context "including a valid state transition" do
             before do
               message['shipment']['status'] = 'canceled'