Consider promotions in default shipping calculator

Previously, the shipment_total method on order was used, which does
not take into account shipment promotions. Instead, we should manually
sum the shipment cost taking into account any adjustments.

Co-authored-by: Nick Van Doorn <nick@super.gd>

3 files changed, 11 insertions, 4 deletions

diff --git a/lib/super_good/solidus_taxjar.rb b/lib/super_good/solidus_taxjar.rb
index 36b5d85..a3cb730 100644
--- a/lib/super_good/solidus_taxjar.rb
+++ b/lib/super_good/solidus_taxjar.rb
@@ -44,7 +44,7 @@ module SuperGood
     }
     self.line_item_tax_label_maker = ->(taxjar_line_item, spree_line_item) { "Sales Tax" }
     self.logging_enabled = false
-    self.shipping_calculator = ->(order) { order.shipment_total }
+    self.shipping_calculator = ->(order) { order.shipments.sum(&:total_before_tax) }
     self.shipping_tax_label_maker = ->(shipment, shipping_tax) { "Sales Tax" }
     self.taxable_address_check = ->(address) { true }
     self.taxable_order_check = ->(order) { true }
diff --git a/spec/super_good/solidus_taxjar/api_params_spec.rb b/spec/super_good/solidus_taxjar/api_params_spec.rb
index 6c13e03..1e879e7 100644
--- a/spec/super_good/solidus_taxjar/api_params_spec.rb
+++ b/spec/super_good/solidus_taxjar/api_params_spec.rb
@@ -8,9 +8,9 @@ RSpec.describe SuperGood::SolidusTaxjar::ApiParams do
       line_items: [line_item],
       number: "R111222333",
       ship_address: ship_address,
-      shipment_total: BigDecimal("3.01"),
       store: store,
       total: order_total,
+      shipments: [shipment],
       user_id: 12345
     ).tap do |order|
       order.update! completed_at: DateTime.new(2018, 3, 6, 12, 10, 33)
@@ -119,6 +119,8 @@ RSpec.describe SuperGood::SolidusTaxjar::ApiParams do
     )
   end
 
+  let(:shipment) { Spree::Shipment.create!(cost: BigDecimal("3.01")) }
+
   describe "#order_params" do
     subject { described_class.order_params(order) }
 
diff --git a/spec/super_good/solidus_taxjar_spec.rb b/spec/super_good/solidus_taxjar_spec.rb
index 7fe0dee..d9ef1d4 100644
--- a/spec/super_good/solidus_taxjar_spec.rb
+++ b/spec/super_good/solidus_taxjar_spec.rb
@@ -77,9 +77,14 @@ RSpec.describe SuperGood::SolidusTaxjar do
     describe ".shipping_calculator" do
       subject { described_class.shipping_calculator.call(order) }
 
-      let(:order) { instance_double(Spree::Order, shipment_total: 10) }
+      let(:order) { create :order }
+      let(:shipment) { create :shipment, order: order, cost: 20 }
 
-      it "returns the shipment total" do
+      before do
+        create :adjustment, order: order, adjustable: shipment, amount: -10, eligible: true, source: create(:shipping_rate, shipment: shipment)
+      end
+
+      it "returns the shipment total including promotions" do
         expect(subject).to eq(10)
       end
     end