Bring estimator from spree_core

app/models/spree/stock/estimator.rb

@@ -0,0 +1,50 @@
+module Spree
+  module Stock
+    class Estimator
+      attr_reader :order, :currency
+
+      def initialize(order)
+        @order = order
+        @currency = order.currency
+      end
+
+      def shipping_rates(package, frontend_only = true)
+        shipping_rates = Array.new
+        shipping_methods = shipping_methods(package)
+        return [] unless shipping_methods
+
+        shipping_methods.each do |shipping_method|
+          cost = calculate_cost(shipping_method, package)
+          shipping_rates << shipping_method.shipping_rates.new(:cost => cost) unless cost.nil?
+        end
+
+        shipping_rates.sort_by! { |r| r.cost || 0 }
+
+        unless shipping_rates.empty?
+          if frontend_only
+            shipping_rates.each do |rate|
+              rate.selected = true and break if rate.shipping_method.frontend?
+            end
+          else
+            shipping_rates.first.selected = true
+          end
+        end
+
+        shipping_rates
+      end
+
+      private
+      def shipping_methods(package)
+        shipping_methods = package.shipping_methods
+        shipping_methods.delete_if { |ship_method| !ship_method.calculator.available?(package) }
+        shipping_methods.delete_if { |ship_method| !ship_method.include?(order.ship_address) }
+        shipping_methods.delete_if { |ship_method| !(ship_method.calculator.preferences[:currency].nil? || ship_method.calculator.preferences[:currency] == currency) }
+        shipping_methods
+      end
+
+      def calculate_cost(shipping_method, package)
+        shipping_method.calculator.compute(package)
+      end
+    end
+  end
+end

spec/models/spree/stock/estimator_spec.rb

@@ -0,0 +1,100 @@
+require 'spec_helper'
+
+module Spree
+  module Stock
+    describe Estimator do
+      let!(:shipping_method) { create(:shipping_method) }
+      let(:package) { build(:stock_package_fulfilled) }
+      let(:order) { package.order }
+      subject { Estimator.new(order) }
+
+      context "#shipping rates" do
+        before(:each) do
+          shipping_method.zones.first.members.create(:zoneable => order.ship_address.country)
+          ShippingMethod.any_instance.stub_chain(:calculator, :available?).and_return(true)
+          ShippingMethod.any_instance.stub_chain(:calculator, :compute).and_return(4.00)
+          ShippingMethod.any_instance.stub_chain(:calculator, :preferences).and_return({:currency => "USD"})
+          ShippingMethod.any_instance.stub_chain(:calculator, :marked_for_destruction?)
+
+          package.stub(:shipping_methods => [shipping_method])
+        end
+
+        it "returns shipping rates from a shipping method if the order's ship address is in the same zone" do
+          shipping_rates = subject.shipping_rates(package)
+          shipping_rates.first.cost.should eq 4.00
+        end
+
+        it "does not return shipping rates from a shipping method if the order's ship address is in a different zone" do
+          shipping_method.zones.each{|z| z.members.delete_all}
+          shipping_rates = subject.shipping_rates(package)
+          shipping_rates.should == []
+        end
+
+        it "does not return shipping rates from a shipping method if the calculator is not available for that order" do
+          ShippingMethod.any_instance.stub_chain(:calculator, :available?).and_return(false)
+          shipping_rates = subject.shipping_rates(package)
+          shipping_rates.should == []
+        end
+
+        it "returns shipping rates from a shipping method if the currency matches the order's currency" do
+          shipping_rates = subject.shipping_rates(package)
+          shipping_rates.first.cost.should eq 4.00
+        end
+
+        it "does not return shipping rates from a shipping method if the currency is different than the order's currency" do
+          order.currency = "GBP"
+          shipping_rates = subject.shipping_rates(package)
+          shipping_rates.should == []
+        end
+
+        it "sorts shipping rates by cost" do
+          shipping_methods = 3.times.map { create(:shipping_method) }
+          shipping_methods[0].stub_chain(:calculator, :compute).and_return(5.00)
+          shipping_methods[1].stub_chain(:calculator, :compute).and_return(3.00)
+          shipping_methods[2].stub_chain(:calculator, :compute).and_return(4.00)
+
+          subject.stub(:shipping_methods).and_return(shipping_methods)
+
+          expect(subject.shipping_rates(package).map(&:cost)).to eq %w[3.00 4.00 5.00].map(&BigDecimal.method(:new))
+        end
+
+        context "general shipping methods" do
+          let(:shipping_methods) { 2.times.map { create(:shipping_method) } }
+
+          it "selects the most affordable shipping rate" do
+            shipping_methods[0].stub_chain(:calculator, :compute).and_return(5.00)
+            shipping_methods[1].stub_chain(:calculator, :compute).and_return(3.00)
+
+            subject.stub(:shipping_methods).and_return(shipping_methods)
+
+            expect(subject.shipping_rates(package).sort_by(&:cost).map(&:selected)).to eq [true, false]
+          end
+
+          it "selects the most affordable shipping rate and doesn't raise exception over nil cost" do
+            shipping_methods[0].stub_chain(:calculator, :compute).and_return(1.00)
+            shipping_methods[1].stub_chain(:calculator, :compute).and_return(nil)
+
+            subject.stub(:shipping_methods).and_return(shipping_methods)
+
+            subject.shipping_rates(package)
+          end
+        end
+
+        context "involves backend only shipping methods" do
+          let(:backend_method) { create(:shipping_method, display_on: "back_end") }
+          let(:generic_method) { create(:shipping_method) }
+
+          # regression for #3287
+          it "doesn't select backend rates even if they're more affordable" do
+            backend_method.stub_chain(:calculator, :compute).and_return(0.00)
+            generic_method.stub_chain(:calculator, :compute).and_return(5.00)
+
+            subject.stub(:shipping_methods).and_return([backend_method, generic_method])
+
+            expect(subject.shipping_rates(package).map(&:selected)).to eq [false, true]
+          end
+        end
+      end
+    end
+  end
+end