text: # Copyright (c) 2018 gevent community
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  # THE SOFTWARE.
  from __future__ import absolute_import, print_function, division
  
  import sys
  import functools
  import unittest
  
  from gevent.util import dump_stacks
  
  from greentest import sysinfo
  from greentest import six
  
  class FlakyAssertionError(AssertionError):
      "Re-raised so that we know it's a known-flaky test."
  
  # The next exceptions allow us to raise them in a highly
  # greppable way so that we can debug them later.
  
  class FlakyTest(unittest.SkipTest):
      """
      A unittest exception that causes the test to be skipped when raised.
  
      Use this carefully, it is a code smell and indicates an undebugged problem.
      """
  
  class FlakyTestRaceCondition(FlakyTest):
      """
      Use this when the flaky test is definitely caused by a race condition.
      """
  
  class FlakyTestTimeout(FlakyTest):
      """
      Use this when the flaky test is definitely caused by an
      unexpected timeout.
      """
  
  class FlakyTestCrashes(FlakyTest):
      """
      Use this when the test sometimes crashes.
      """
  
  def reraiseFlakyTestRaceCondition():
      six.reraise(FlakyAssertionError,
                  FlakyAssertionError(sys.exc_info()[1]),
                  sys.exc_info()[2])
  
  reraiseFlakyTestTimeout = reraiseFlakyTestRaceCondition
  reraiseFlakyTestRaceConditionLibuv = reraiseFlakyTestRaceCondition
  reraiseFlakyTestTimeoutLibuv = reraiseFlakyTestRaceCondition
  
  if sysinfo.RUNNING_ON_CI or (sysinfo.PYPY and sysinfo.WIN):
      # pylint: disable=function-redefined
      def reraiseFlakyTestRaceCondition():
          if sysinfo.PYPY and sysinfo.WIN:
              # Getting stack traces is incredibly expensive
              # in pypy on win, at least in test virtual machines.
              # It can take minutes. The traceback consistently looks like
              # the following when interrupted:
  
              # dump_stacks -> traceback.format_stack
              #    -> traceback.extract_stack -> linecache.checkcache
              #    -> os.stat -> _structseq.structseq_new
              msg = str(sys.exc_info()[1])
          else:
              msg = '\n'.join(dump_stacks())
          six.reraise(FlakyTestRaceCondition,
                      FlakyTestRaceCondition(msg),
                      sys.exc_info()[2])
  
      def reraiseFlakyTestTimeout():
          msg = str(sys.exc_info()[1])
          six.reraise(FlakyTestTimeout,
                      FlakyTestTimeout(msg),
                      sys.exc_info()[2])
  
      if sysinfo.LIBUV:
          reraiseFlakyTestRaceConditionLibuv = reraiseFlakyTestRaceCondition
          reraiseFlakyTestTimeoutLibuv = reraiseFlakyTestTimeout
  
  
  def reraises_flaky_timeout(exc_kind):
  
      def wrapper(f):
          @functools.wraps(f)
          def m(*args):
              try:
                  f(*args)
              except exc_kind:
                  reraiseFlakyTestTimeout()
          return m
  
      return wrapper
  