Working scopes for child variant and master variants

lib/open_food_network/products_and_inventory_report.rb

@@ -39,5 +39,14 @@ module OpenFoodNetwork
       .joins(:product)
       .merge(Spree::Product.managed_by(@user))
     end
+
+    def master_variants
+      Spree::Variant.where(:is_master => true)
+      .joins(:product)
+      .where("(select spree_variants.id from spree_variants as other_spree_variants
+                  WHERE other_spree_variants.product_id = spree_variants.product_id
+                 AND other_spree_variants.is_master = 'f' LIMIT 1) IS NULL")
+      .merge(Spree::Product.managed_by(@user))
+    end
   end
 end

spec/lib/open_food_network/products_and_inventory_report_spec.rb

@@ -73,6 +73,22 @@ module OpenFoodNetwork
         end
       end
 
+      describe "fetching master variants" do
+        it "should only return variants managed by the user" do
+          product1 = create(:simple_product, supplier: create(:supplier_enterprise))
+          product2 = create(:simple_product, supplier: supplier)
+          
+          subject.master_variants.should == [product2.master]
+        end
+
+        it "doesn't return master variants with siblings" do
+          product = create(:simple_product, supplier: supplier)
+          create(:variant, product: product)  
+          
+          subject.master_variants.should be_empty 
+        end
+      end
+
     end
     
     it "should fetch variants"