corrected special_item method and added further test for this.

ruby/lib/gilded_rose.rb

@@ -43,6 +43,7 @@ class GildedRose
 
           if !item.name.downcase.match /backstage/
             update_normal_quality(item) unless sulfuras?(item)
+
           else
             item.quality = 0
           end
@@ -67,7 +68,7 @@ class GildedRose
   end
 
   def self.special_item?(item)
-    !item.name.downcase.match( /Aged Brie/ || /backstage/) || !sulfuras?(item)
+    item.name.downcase.match( /Aged Brie/ || /backstage/).nil? || sulfuras?(item)
   end
 end
 

ruby/spec/gilded_rose_spec.rb

@@ -120,7 +120,7 @@ let(:sulfarus) { Item.new('Sulfuras, Hand of Ragnaros', 50, 80) }
     end
 
     it 'returns true for backstage passes' do
-      item_double = double :item, name: "backstage pass for gong party"
+      item_double = double :item, name: "Backstage passes to a TAFKAL80ETC concert"
       expect(GildedRose.special_item?(item_double)).to eq true
     end
 
@@ -128,6 +128,11 @@ let(:sulfarus) { Item.new('Sulfuras, Hand of Ragnaros', 50, 80) }
       sulfuras_double = double :selfarus, name: 'Sulfuras'
       expect(GildedRose.special_item?(sulfuras_double)).to eq true
     end 
+
+    it 'returns false on potato' do
+      item_double = double :item, name: "potato"
+      expect(GildedRose.sulfuras?(item_double)).to eq false
+    end
   end