Set transaction fee adjustments to ineligible if payment is invalid or failed

app/models/spree/payment_decorator.rb

@@ -7,12 +7,10 @@ module Spree
     attr_accessible :source
 
     def ensure_correct_adjustment
-      # Don't charge for invalid payments.
-      # PayPalExpress always creates a payment that is invalidated later.
-      # Unknown: What about failed payments?
-      if state == "invalid"
-        adjustment.andand.destroy
-      elsif adjustment
+      revoke_adjustment_eligibility if ['failed', 'invalid'].include?(state)
+      return if adjustment.try(:finalized?)
+
+      if adjustment
         adjustment.originator = payment_method
         adjustment.label = adjustment_label
         adjustment.save
@@ -101,5 +99,16 @@ module Spree
     rescue ActiveMerchant::ConnectionError => e
       gateway_error e
     end
+
+    # Don't charge fees for invalid or failed payments.
+    # This is called twice for failed payments, because the persistence of the 'failed'
+    # state is acheived through some trickery using an after_rollback callback on the
+    # payment model. See Spree::Payment#persist_invalid
+    def revoke_adjustment_eligibility
+      return unless adjustment.reload
+      return if adjustment.finalized?
+      adjustment.update_attribute(:eligible, false)
+      adjustment.finalize!
+    end
   end
 end

spec/models/spree/payment_spec.rb

@@ -124,5 +124,89 @@ module Spree
         payment.refund!
       end
     end
+
+    describe "applying transaction fees" do
+      let!(:order) { create(:order) }
+      let!(:line_item) { create(:line_item, order: order, quantity: 3, price: 5.00) }
+
+      before do
+        order.reload.update!
+      end
+
+      context "to Stripe payments" do
+        let(:shop) { create(:enterprise) }
+        let(:payment_method) { create(:stripe_payment_method, distributor_ids: [create(:distributor_enterprise).id], preferred_enterprise_id: shop.id) }
+        let(:payment) { create(:payment, order: order, payment_method: payment_method, amount: order.total) }
+        let(:calculator) { Spree::Calculator::FlatPercentItemTotal.new(preferred_flat_percent: 10) }
+
+        before do
+          payment_method.calculator = calculator
+          payment_method.save!
+
+          allow(order).to receive(:pending_payments) { [payment] }
+        end
+
+        context "when the payment fails" do
+          let(:failed_response) { ActiveMerchant::Billing::Response.new(false, "This is an error message") }
+
+          before do
+            allow(payment_method).to receive(:purchase) { failed_response }
+          end
+
+          it "makes the transaction fee ineligible and finalizes it" do
+            # Decided to wrap the save process in order.process_payments!
+            # since that is the context it is usually performed in
+            order.process_payments!
+            expect(order.payments.count).to eq 1
+            expect(order.payments).to include payment
+            expect(payment.state).to eq "failed"
+            expect(payment.adjustment.eligible?).to be false
+            expect(payment.adjustment.finalized?).to be true
+            expect(order.adjustments.payment_fee.count).to eq 1
+            expect(order.adjustments.payment_fee.eligible).to_not include payment.adjustment
+          end
+        end
+
+        context "when the payment information is invalid" do
+          before do
+            allow(payment_method).to receive(:supports?) { false }
+          end
+
+          it "makes the transaction fee ineligible and finalizes it" do
+            # Decided to wrap the save process in order.process_payments!
+            # since that is the context it is usually performed in
+            order.process_payments!
+            expect(order.payments.count).to eq 1
+            expect(order.payments).to include payment
+            expect(payment.state).to eq "invalid"
+            expect(payment.adjustment.eligible?).to be false
+            expect(payment.adjustment.finalized?).to be true
+            expect(order.adjustments.payment_fee.count).to eq 1
+            expect(order.adjustments.payment_fee.eligible).to_not include payment.adjustment
+          end
+        end
+
+        context "when the payment is processed successfully" do
+          let(:successful_response) { ActiveMerchant::Billing::Response.new(true, "Yay!") }
+
+          before do
+            allow(payment_method).to receive(:purchase) { successful_response }
+          end
+
+          it "creates an appropriate adjustment" do
+            # Decided to wrap the save process in order.process_payments!
+            # since that is the context it is usually performed in
+            order.process_payments!
+            expect(order.payments.count).to eq 1
+            expect(order.payments).to include payment
+            expect(payment.state).to eq "completed"
+            expect(payment.adjustment.eligible?).to be true
+            expect(order.adjustments.payment_fee.count).to eq 1
+            expect(order.adjustments.payment_fee.eligible).to include payment.adjustment
+            expect(payment.adjustment.amount).to eq 1.5
+          end
+        end
+      end
+    end
   end
 end