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
-
-    #ap "Original n_contenders = #{n_contenders}"
-    while n_contenders % 4 != 0
-      n_contenders -= 1
+  def valid_number_of_contenders?(n_contenders)
+    [8, 16, 32, 64, 128].include?(n_contenders)
   end
 
-    #ap "Resulting n_contenders divisible by 4 = #{n_contenders}"
+  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
 
     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

rails/map-mash/spec/models/mash_tournament_spec.rb

@@ -5,29 +5,42 @@ describe MashTournament do
     @valid_attributes = {:requester_id => 1}
   end
 
-  it "should create a new instance given valid attributes" do
-    MashTournament.create!(@valid_attributes)
-  end
-
-  context 'creating rounds' do
-    before(:all) do
-      Map.destroy_all
-      8.times do
-        Map.make.save
-      end
+  before(:each) do
     @requester = Requester.make
     @requester.save!
-    end
-
-    before(:each) do
     subject.requester_id = @requester.id
     subject.save!
     subject.reload
   end
 
-    it 'should create 3 rounds for 8 contenders' do
-      subject.create_rounds
-      subject.total_rounds.should == 3
+  it "should create a new instance given valid attributes" do
+    MashTournament.create!(@valid_attributes)
+  end
+
+  context 'creating rounds' do
+
+    it 'should reject invalid numbers of contenders' do
+      [11, 24, 40].each do |n|
+        expect do
+          subject.create_rounds(n)
+        end.to raise_error
+      end
+    end
+
+    before(:all) do
+      Map.destroy_all
+      40.times do
+        Map.make.save
+      end
+    end
+
+    [[8, 3], [16, 4], [32, 5]].each do |n_contenders,n_rounds|
+      context "for #{n_contenders} total contenders" do
+        it "should create #{n_rounds} rounds" do
+          subject.create_rounds(n_contenders)
+          subject.total_rounds.should == n_rounds
+        end
+      end
     end
   end
 end