2 files changed, 121 insertions, 16 deletions
diff --git a/lib/super_good/solidus_taxjar/tax_calculator.rb b/lib/super_good/solidus_taxjar/tax_calculator.rb
index e2a398e..e498da0 100644
--- a/lib/super_good/solidus_taxjar/tax_calculator.rb
+++ b/lib/super_good/solidus_taxjar/tax_calculator.rb
@@ -1,28 +1,60 @@
 module SuperGood
   module SolidusTaxJar
     class TaxCalculator
-      def initialize(order)
+      def self.default_api
+        ::SuperGood::SolidusTaxJar::API.new
+      end
+
+      def initialize(order, api: self.class.default_api)
         @order = order
+        @api = api
       end
 
       def calculate
+        return no_tax if order.tax_address.empty?
+        return no_tax unless taxjar_breakdown
+
         Spree::Tax::OrderTax.new(
           order_id: order.id,
-          line_item_taxes: line_item_rates,
-          shipment_taxes: shipment_rates
+          line_item_taxes: line_item_taxes,
+          shipment_taxes: []
         )
       end
 
       private
 
-      attr_reader :order
+      attr_reader :order, :api
+
+      def line_item_taxes
+        taxjar_breakdown.line_items.map do |line_item|
+          Spree::Tax::ItemTax.new(
+            item_id: line_item.id.to_i,
+            label: "Sales Tax",
+            tax_rate: tax_rate,
+            amount: line_item.tax_collectable,
+            included_in_price: false
+          )
+        end
+      end
+
+      def taxjar_breakdown
+        @taxjar_breakdown ||= taxjar_tax.breakdown
+      end
+
+      def taxjar_tax
+        @taxjar_taxes ||= api.tax_for(order)
+      end
 
-      def line_item_rates
-        []
+      def no_tax
+        Spree::Tax::OrderTax.new(
+          order_id: order.id,
+          line_item_taxes: [],
+          shipment_taxes: []
+        )
       end
 
-      def shipment_rates
-        []
+      def tax_rate
+        Spree::TaxRate.find_by(name: "Sales Tax")
       end
     end
   end
diff --git a/spec/super_good/solidus_taxjar/tax_calculator_spec.rb b/spec/super_good/solidus_taxjar/tax_calculator_spec.rb
index eaf810c..02140da 100644
--- a/spec/super_good/solidus_taxjar/tax_calculator_spec.rb
+++ b/spec/super_good/solidus_taxjar/tax_calculator_spec.rb
@@ -1,21 +1,94 @@
 require 'spec_helper'
 
-RSpec.describe SuperGood::SolidusTaxJar::TaxCalculator do
+RSpec.describe ::SuperGood::SolidusTaxJar::TaxCalculator do
   describe "#calculate" do
     subject { calculator.calculate }
 
-    let(:calculator) { described_class.new(order) }
+    let(:calculator) { described_class.new(order, api: dummy_api) }
+
+    let(:dummy_api) do
+      instance_double ::SuperGood::SolidusTaxJar::API
+    end
 
     let(:order) do
-      Spree::Order.new(
-        id: 10
+      ::Spree::Order.new(
+        id: 10,
+        store: store,
+        ship_address: address
+      )
+    end
+
+    let(:store) do
+      ::Spree::Store.new(
+        name: "Default Store",
+        url: "https://store.example.com",
+        code: "store",
+        mail_from_address: "contact@example.com",
+        cart_tax_country_iso: "US"
       )
     end
 
-    it "returns the taxes" do
-      expect(subject.order_id).to eq order.id
-      expect(subject.line_item_taxes).to be_empty
-      expect(subject.shipment_taxes).to be_empty
+    context "when the order has an empty tax address" do
+      let(:address) { nil }
+
+      it "returns no taxes" do
+        expect(subject.order_id).to eq order.id
+        expect(subject.shipment_taxes).to be_empty
+        expect(subject.line_item_taxes).to be_empty
+      end
+    end
+
+    context "when the order has a non-empty tax address" do
+      let(:address) { ::Spree::Address.new(first_name: "Ronnie James") }
+
+      before do
+        allow(dummy_api).to receive(:tax_for).with(order).and_return(
+          instance_double(::Taxjar::Tax, breakdown: breakdown)
+        )
+      end
+
+      context "and there is a breakdown" do
+        let!(:tax_rate) do
+          ::Spree::TaxRate.create!(
+            name: "Sales Tax",
+            amount: 0.5,
+            calculator: ::Spree::Calculator.new
+          )
+        end
+
+        let(:breakdown) do
+          instance_double ::Taxjar::Breakdown, line_items: [taxjar_line_item]
+        end
+
+        let(:taxjar_line_item) do
+          instance_double ::Taxjar::BreakdownLineItem, id: "33", tax_collectable: 6.66
+        end
+
+        it "returns the taxes" do
+          expect(subject.order_id).to eq order.id
+          expect(subject.shipment_taxes).to be_empty
+          expect(subject.line_item_taxes.length).to eq 1
+
+          item_tax = subject.line_item_taxes.first
+          aggregate_failures do
+            expect(item_tax.item_id).to eq 33
+            expect(item_tax.label).to eq "Sales Tax"
+            expect(item_tax.tax_rate).to eq tax_rate
+            expect(item_tax.amount).to eq 6.66
+            expect(item_tax.included_in_price).to eq false
+          end
+        end
+      end
+
+      context "and there is not a breakdown" do
+        let(:breakdown) { nil }
+
+        it "returns no taxes" do
+          expect(subject.order_id).to eq order.id
+          expect(subject.shipment_taxes).to be_empty
+          expect(subject.line_item_taxes).to be_empty
+        end
+      end
     end
   end
 end