class FoodCritic::ContextOutput

def key_by_file_and_line(review)
  warn_hash = {}
  review.warnings.each do |warning|
    filename = Pathname.new(warning.match[:filename]).cleanpath.to_s
    line_num = warning.match[:line].to_i
    warn_hash[filename] = {} unless warn_hash.key?(filename)
    unless warn_hash[filename].key?(line_num)
      warn_hash[filename][line_num] = Set.new
    end
    warn_hash[filename][line_num] << warning.rule
  end
  warn_hash
end