implement a sliding window of questions, so earlier questions are dro…

…pped as later ones are introduced. Issue rchatley#2

lib/extreme_startup/question_factory.rb

@@ -390,7 +390,9 @@ def initialize
     end
 
     def next_question(player)
-      available_question_types = @question_types[0..(@round * 2 - 1)]
+      window_end = (@round * 2 - 1)
+      window_start = [0, window_end - 4].max
+      available_question_types = @question_types[window_start..window_end]
       available_question_types.sample.new(player)
     end
 

spec/extreme_startup/question_factory_spec.rb

@@ -31,6 +31,25 @@ module ExtremeStartup
         end
 
     end
+
+    context "in the third round" do
+      before(:each) do
+        factory.advance_round
+        factory.advance_round
+      end
+
+       it "moves a sliding window forward, keeping 5 question types, so AdditionQuestions no longer appear" do
+          questions = 30.times.map { factory.next_question(player) }
+          questions.any? { |q| q.is_a?(AdditionQuestion) }.should be_false
+          questions.any? { |q| q.is_a?(MaximumQuestion) }.should be_true
+          questions.any? { |q| q.is_a?(MultiplicationQuestion) }.should be_true
+          questions.any? { |q| q.is_a?(SquareCubeQuestion) }.should be_true
+          questions.any? { |q| q.is_a?(MultiplicationQuestion) }.should be_true
+          questions.any? { |q| q.is_a?(SquareCubeQuestion) }.should be_true
+          questions.all? { |q| [MaximumQuestion, MultiplicationQuestion, SquareCubeQuestion, GeneralKnowledgeQuestion, PrimesQuestion].include? q.class }
+        end
+
+    end
 
   end
 end