Tiltfile

def local_output(command):
  return str(local(command, echo_off=True, quiet=True)).rstrip('\n')

ordinals = {
  1: 'st',
  2: 'nd',
  3: 'rd',
}

def print_status(retry_count, expected_output, actual_output):
    print('{}{} retry'.format(retry_count, ordinals.get(retry_count, 'th')))
    print('-----------------------')
    print('| Expected output: {}'.format(expected_output))
    print('| Actual output  : {}'.format(actual_output))
    print('-----------------------')

def wait_for_it(command, expected_output, backoff=1000, retry_limit=5):
  print('+--+-+-+-+-+-+-+-+-+-+-+')
  print('Waiting for \'{}\' to output: \'{}\''.format(command, expected_output))
  for i in range(retry_limit):
    actual_output = local_output(command)
    print_status(i+1, expected_output, actual_output)
    if actual_output == expected_output:
      print('Output expectation successfully met!')
      return
    print('Sleeping for {}ms'.format(backoff))
    local('sleep {}'.format(backoff//1000), quiet=True, echo_off=True)
    print('\n+--+-+-+-+-+-+-+-+-+-+-+\n')
  fail('Retry limit exceeded!')