def select_for_test(readers=nil, writers=nil, errors=nil, wait=nil)
ready_readers = Array(readers).select { |r| r.select_for_read? }
ready_writers = Array(writers).select { |r| r.select_for_write? }
ready_errors = Array(errors).select { |r| r.select_for_error? }
if ready_readers.any? || ready_writers.any? || ready_errors.any?
return [ready_readers, ready_writers, ready_errors]
end
processed = 0
Array(readers).each do |reader|
processed += 1 if reader.idle!
end
raise "no readers were ready for reading, and none had any incoming packets" if processed == 0
end