+ candidates=election.candidates.collect { |c| c.id }
+ vote_list[0].each do |vote|
+ raise ArgumentError.new("Invalid Candidate ID #{vote}") unless candidates.index(vote)
+ end
+ raise ArgumentError.new("You must rank all candidates") unless candidates.length <= vote_list[0].length
+ raise ArgumentError.new("Please rank each candidate only once") if vote_list[0].uniq!