Stick this in your .irbrc and smoke it

methods_returning.rb

def methods_returning(answer, *args)
  # probably want to filter out some methods
  # e.g. ones that mutate their receiver...
  blacklist = %w()

  (methods - blacklist).select do |method|
    guinea_pig = begin
                   clone
                 rescue TypeError => e
                   raise unless e.message =~ /can't clone/
                   self
                 end
    begin
      guinea_pig.send(method, *args) == answer
    rescue ArgumentError, LocalJumpError
    rescue TypeError, NoMethodError, NameError, IndexError, SystemCallError, NotImplementedError => e
      args_inspected = args.inspect
      args_nice = args_inspected[1, args_inspected.length - 2]
      puts "#{self.inspect}.#{method}(#{args_nice}) throws #{e.class}: #{e}"
    end
  end
end