Merge pull request #3640 from nebulab/spaghetticode/order-shipping-di…

…scount

Make Order#shipping_discount consider only credits

core/app/models/spree/order.rb

@@ -229,7 +229,7 @@ def currency
     end
 
     def shipping_discount
-      shipment_adjustments.eligible.sum(:amount) * - 1
+      shipment_adjustments.credit.eligible.sum(:amount) * - 1
     end
 
     def to_param

core/spec/models/spree/order_spec.rb

@@ -1720,4 +1720,19 @@ def generate
       end.to change { subject.shipments.count }.by 1
     end
   end
+
+  describe '#shipping_discount' do
+    let(:shipment) { create(:shipment) }
+    let(:order) { shipment.order }
+
+    let!(:charge_shipment_adjustment) { create :adjustment, adjustable: shipment, amount: 20 }
+    let!(:shipment_adjustment) { create :adjustment, adjustable: shipment, amount: -10 }
+    let!(:other_shipment_adjustment) { create :adjustment, adjustable: shipment, amount: -30 }
+
+    subject { order.shipping_discount }
+
+    it 'sums eligible shipping adjustments with negative amount (credit)' do
+      expect(subject).to eq 40
+    end
+  end
 end