add tests for ranking position

app/controllers/champions_controller.rb

@@ -13,11 +13,11 @@ def ranking
     role = champion_params[:lane]
     list_position = champion_params[:list_position].to_i
     list_size = champion_params[:list_size].to_i
-    list_position = RANKING_LIST_POSITION unless list_position.positive?
+    list_position = RANKING_LIST_POSITION unless list_position > 0
     list_size = RANKING_LIST_SIZE unless list_size.positive?
 
     champions = Rails.cache.read(:champions)
-    rankings = Rails.cache.read({ rankings: role })[list_position..-1]
+    rankings = Rails.cache.read({ rankings: role })[(list_position - 1)..-1]
       .first(list_size)
 
     ranking_message = rankings.map do |key|

spec/controllers/champions_controller_spec.rb

@@ -179,10 +179,24 @@ def speech
   describe 'POST ranking' do
     let(:action) { :ranking }
 
+    context 'with list position specified' do
+      before :each do
+        allow(controller).to receive(:champion_params).and_return({
+          list_size: '1',
+          lane: 'Top',
+          list_position: '2'
+        })
+      end
+
+      it 'should determine the best champion at that list position' do
+        post action, params
+        expect(speech).to eq "The second best champion in Top is Nasus."
+      end
+    end
+
     context 'with list size specified' do
       it 'determine the best champions for the specified list size and role' do
         post action, params
-
         expect(speech).to eq "The best three champions in Top are Darius, Nasus, and Jayce."
       end
     end