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"""A utility useful in tests of asynchronous, event-driven interfaces."""

import threading

from grpc.framework.foundation import stream


class Callback(stream.Consumer):
  """A utility object useful in tests of asynchronous code."""

  def __init__(self):
    self._condition = threading.Condition()
    self._unary_response = None
    self._streamed_responses = []
    self._completed = False
    self._abortion = None

  def abort(self, abortion):
    with self._condition:
      self._abortion = abortion
      self._condition.notify_all()

  def complete(self, unary_response):
    with self._condition:
      self._unary_response = unary_response
      self._completed = True
      self._condition.notify_all()

  def consume(self, streamed_response):
    with self._condition:
      self._streamed_responses.append(streamed_response)

  def terminate(self):
    with self._condition:
      self._completed = True
      self._condition.notify_all()

  def consume_and_terminate(self, streamed_response):
    with self._condition:
      self._streamed_responses.append(streamed_response)
      self._completed = True
      self._condition.notify_all()

  def block_until_terminated(self):
    with self._condition:
      while self._abortion is None and not self._completed:
        self._condition.wait()

  def response(self):
    with self._condition:
      if self._abortion is None:
        return self._unary_response
      else:
        raise AssertionError('Aborted with abortion "%s"!' % self._abortion)

  def responses(self):
    with self._condition:
      if self._abortion is None:
        return list(self._streamed_responses)
      else:
        raise AssertionError('Aborted with abortion "%s"!' % self._abortion)

  def abortion(self):
    with self._condition:
      return self._abortion