Add dummy calculator

This implements the interface required by Solidus, however it currently
just reports no taxes.

3 files changed, 51 insertions, 0 deletions

diff --git a/lib/super_good/solidus_taxjar.rb b/lib/super_good/solidus_taxjar.rb
index 5ed9bd4..6553213 100644
--- a/lib/super_good/solidus_taxjar.rb
+++ b/lib/super_good/solidus_taxjar.rb
@@ -8,3 +8,4 @@ module SuperGood
 end
 
 require "super_good/solidus_taxjar/version"
+require "super_good/solidus_taxjar/tax_calculator"
diff --git a/lib/super_good/solidus_taxjar/tax_calculator.rb b/lib/super_good/solidus_taxjar/tax_calculator.rb
new file mode 100644
index 0000000..e2a398e
--- /dev/null
+++ b/lib/super_good/solidus_taxjar/tax_calculator.rb
@@ -0,0 +1,29 @@
+module SuperGood
+  module SolidusTaxJar
+    class TaxCalculator
+      def initialize(order)
+        @order = order
+      end
+
+      def calculate
+        Spree::Tax::OrderTax.new(
+          order_id: order.id,
+          line_item_taxes: line_item_rates,
+          shipment_taxes: shipment_rates
+        )
+      end
+
+      private
+
+      attr_reader :order
+
+      def line_item_rates
+        []
+      end
+
+      def shipment_rates
+        []
+      end
+    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
new file mode 100644
index 0000000..eaf810c
--- /dev/null
+++ b/spec/super_good/solidus_taxjar/tax_calculator_spec.rb
@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+RSpec.describe SuperGood::SolidusTaxJar::TaxCalculator do
+  describe "#calculate" do
+    subject { calculator.calculate }
+
+    let(:calculator) { described_class.new(order) }
+
+    let(:order) do
+      Spree::Order.new(
+        id: 10
+      )
+    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
+    end
+  end
+end