Don't consider order total when it is canceled

app/services/customers_with_balance.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CustomersWithBalance
   def initialize(enterprise_id)
     @enterprise_id = enterprise_id
@@ -6,14 +8,22 @@ class CustomersWithBalance
   def query
     Customer.of(enterprise_id).
       includes(:bill_address, :ship_address, user: :credit_cards).
-      joins(:orders).
-      merge(Spree::Order.complete.not_state(:canceled)).
+      joins("LEFT JOIN spree_orders ON spree_orders.customer_id = customers.id").
       group("customers.id").
       select("customers.*").
-      select("SUM(total - payment_total) AS balance_value")
+      select(outstanding_balance)
   end
 
   private
 
   attr_reader :enterprise_id
+
+  def outstanding_balance
+    <<-SQL.strip_heredoc
+       SUM(
+         CASE WHEN state = 'canceled' THEN payment_total
+         ELSE payment_total - total END
+       ) AS balance_value
+    SQL
+  end
 end

spec/services/customers_with_balance_spec.rb

@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe CustomersWithBalance do
+  subject(:customers_with_balance) { described_class.new(customer.enterprise.id) }
+
+  describe '#query' do
+    let(:customer) { create(:customer) }
+
+    context 'when no orders where paid' do
+      let(:total) { 200.00 }
+      let(:order_total) { 100.00 }
+
+      before do
+        create(:order, customer: customer, total: order_total, payment_total: 0)
+        create(:order, customer: customer, total: order_total, payment_total: 0)
+      end
+
+      it 'returns the customer balance' do
+        customer = customers_with_balance.query.first
+        expect(customer.balance_value).to eq(-total)
+      end
+    end
+
+    context 'when an order was paid' do
+      let(:total) { 200.00 }
+      let(:order_total) { 100.00 }
+      let(:payment_total) { order_total }
+
+      before do
+        create(:order, customer: customer, total: order_total, payment_total: 0)
+        create(:order, customer: customer, total: order_total, payment_total: payment_total)
+      end
+
+      it 'returns the customer balance' do
+        customer = customers_with_balance.query.first
+        expect(customer.balance_value).to eq(payment_total - total)
+      end
+    end
+
+    context 'when an order is canceled' do
+      let(:total) { 200.00 }
+      let(:order_total) { 100.00 }
+      let(:payment_total) { 100.00 }
+      let(:complete_orders_total) { order_total }
+
+      before do
+        create(:order, customer: customer, total: order_total, payment_total: 0)
+        create(
+          :order,
+          customer: customer,
+          total: order_total,
+          payment_total: order_total,
+          state: 'canceled'
+        )
+      end
+
+      it 'returns the customer balance' do
+        customer = customers_with_balance.query.first
+        expect(customer.balance_value).to eq(payment_total - complete_orders_total)
+      end
+    end
+  end
+end