lib/vanity/experiment/ab_test.rb in vanity-1.2.0 vs lib/vanity/experiment/ab_test.rb in vanity-1.3.0

@@ -193,12 +193,19 @@
             index = alternative_for(identity)
             redis.sadd key("alts:#{index}:participants"), identity
             check_completion!
           end
         else
-          index = redis[key("outcome")] || alternative_for(identify)
+          index = redis[key("outcome")] || alternative_for(identity)
         end
         @alternatives[index.to_i]
+      end
+
+      # Returns fingerprint (hash) for given alternative.  Can be used to lookup
+      # alternative for experiment without revealing what values are available
+      # (e.g. choosing alternative from HTTP query parameter).
+      def fingerprint(alternative)
+        Digest::MD5.hexdigest("#{id}:#{alternative.id}")[-10,10]
       end
 
       
       # -- Testing --