test_runner.py 文件源码

def WaitUntil(predicate, timeout_seconds=1):
  """Blocks until the provided predicate (function) is true.

  Returns:
    Whether the provided predicate was satisfied once (before the timeout).
  """
  start_time = time.clock()
  sleep_time_sec = 0.025
  while True:
    if predicate():
      return True

    if time.clock() - start_time > timeout_seconds:
      return False

    time.sleep(sleep_time_sec)
    sleep_time_sec = min(1, sleep_time_sec * 2)  # Don't wait more than 1 sec.


# Implementation of chrome_test_server_spawner.PortForwarder that doesn't
# forward ports. Instead the tests are expected to connect to the host IP
# address inside the virtual network provided by qemu. qemu will forward
# these connections to the corresponding localhost ports.