item search throws exception if not given query

app/models/item.rb

@@ -14,6 +14,8 @@ class Item < ActiveRecord::Base
   end
   
   def self.search(query)
+    query = query.strip if query
+    raise ArgumentError, "Please provide a search query" if query.blank?
     query_conditions = [Condition.new]
     in_phrase = false
     query.each_char do |c|

spec/models/item_spec.rb

@@ -147,5 +147,14 @@ describe Item do
           ['One two four', 'Zero one']
         ]
     end
+    
+    specify "should return raise exception for a query with no conditions" do
+      Factory.create :item
+      [
+        lambda { Item.search('').all },
+        lambda { Item.search(nil).all },
+        lambda { Item.search(' ').all }
+      ].each { |l| l.should raise_error(ArgumentError) }
+    end
   end
 end