More work on verifying tournament round generation

rails/map-mash/app/models/mash_tournament.rb

@@ -2,7 +2,6 @@ class MashTournament < ActiveRecord::Base
   belongs_to :requester
   has_many :mashes
   has_many :rounds, :class_name => 'MashTournamentRound'
-  #after_create :create_rounds
   #after_save :fill_in_next_round
 
   def next_unplayed_mash
@@ -19,20 +18,21 @@ class MashTournament < ActiveRecord::Base
     )
   end
 
-  def create_rounds
-    n_contenders = Map.count
+  def valid_number_of_contenders?(n_contenders)
+    [8, 16, 32, 64, 128].include?(n_contenders)
+  end
 
-    #ap "Original n_contenders = #{n_contenders}"
-    while n_contenders % 4 != 0
-      n_contenders -= 1
+  def create_rounds(n_contenders)
+    if not valid_number_of_contenders?(n_contenders)
+      raise StandardError.new(
+        "The number of contenders must be 8, 16, 32, 64, or 128!  " +
+        "Got '#{n_contenders}'"
+      )
     end
 
-    #ap "Resulting n_contenders divisible by 4 = #{n_contenders}"
-
     round = 1
 
     while n_contenders > 1
-      #ap "Generating round #{round}, n_contenders = #{n_contenders}"
       create_round(round, n_contenders)
       n_contenders = n_contenders / 2
       round += 1