Handling tax categories without tax rates

lib/open_food_network/lettuce_share_report.rb

@@ -39,7 +39,7 @@ module OpenFoodNetwork
 
     def gst(variant)
       tax_category = variant.product.tax_category
-      if tax_category
+      if tax_category && tax_category.tax_rates.present?
         tax_rate = tax_category.tax_rates.first
         line_item = mock_line_item(variant, tax_category)
         tax_rate.calculator.compute line_item

spec/lib/open_food_network/lettuce_share_report_spec.rb

@@ -21,5 +21,11 @@ module OpenFoodNetwork
         report.send(:grower_and_method, v).should == "Producer (Method)"
       end
     end
+
+    describe "gst" do
+      it "handles tax category without rates" do
+        report.send(:gst, v).should == 0
+      end
+    end
   end
 end