Find line items with and without tax

app/models/spree/line_item_decorator.rb

@@ -23,6 +23,15 @@ Spree::LineItem.class_eval do
     where('spree_products.supplier_id IN (?)', enterprises)
   }
 
+  scope :with_tax, joins(:adjustments).
+                   where('spree_adjustments.originator_type = ?', 'Spree::TaxRate').
+                   select('DISTINCT spree_line_items.*')
+
+  # Line items without a Spree::TaxRate-originated adjustment
+  scope :without_tax, joins("LEFT OUTER JOIN spree_adjustments ON (spree_adjustments.adjustable_id=spree_line_items.id AND spree_adjustments.adjustable_type = 'Spree::LineItem' AND spree_adjustments.originator_type='Spree::TaxRate')").
+                      where('spree_adjustments.id IS NULL')
+
+
   def price_with_adjustments
     # EnterpriseFee#create_locked_adjustment applies adjustments on line items to their parent order,
     # so line_item.adjustments returns an empty array

spec/models/spree/line_item_spec.rb

@@ -24,6 +24,22 @@ module Spree
         LineItem.supplied_by_any([s2]).should == [li2]
         LineItem.supplied_by_any([s1, s2]).sort.should == [li1, li2].sort
       end
+
+      describe "finding line items with and without tax" do
+        let(:tax_rate) { create(:tax_rate, calculator: Spree::Calculator::DefaultTax.new) }
+        let!(:adjustment1) { create(:adjustment, adjustable: li1, originator: tax_rate, label: "TR", amount: 123, included_tax: 10.00) }
+        let!(:adjustment2) { create(:adjustment, adjustable: li1, originator: tax_rate, label: "TR", amount: 123, included_tax: 10.00) }
+
+        before { li1; li2 }
+
+        it "finds line items with tax" do
+          LineItem.with_tax.should == [li1]
+        end
+
+        it "finds line items without tax" do
+          LineItem.without_tax.should == [li2]
+        end
+      end
     end
 
     describe "calculating price with adjustments" do