src/python/grpcio/tests/unit/test_common.py

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"""Common code used throughout tests of gRPC."""

import collections

import six

INVOCATION_INITIAL_METADATA = ((b'0', b'abc'), (b'1', b'def'), (b'2', b'ghi'),)
SERVICE_INITIAL_METADATA = ((b'3', b'jkl'), (b'4', b'mno'), (b'5', b'pqr'),)
SERVICE_TERMINAL_METADATA = ((b'6', b'stu'), (b'7', b'vwx'), (b'8', b'yza'),)
DETAILS = b'test details'


def metadata_transmitted(original_metadata, transmitted_metadata):
  """Judges whether or not metadata was acceptably transmitted.

  gRPC is allowed to insert key-value pairs into the metadata values given by
  applications and to reorder key-value pairs with different keys but it is not
  allowed to alter existing key-value pairs or to reorder key-value pairs with
  the same key.

  Args:
    original_metadata: A metadata value used in a test of gRPC. An iterable over
      iterables of length 2.
    transmitted_metadata: A metadata value corresponding to original_metadata
      after having been transmitted via gRPC. An iterable over iterables of
      length 2.

  Returns:
     A boolean indicating whether transmitted_metadata accurately reflects
      original_metadata after having been transmitted via gRPC.
  """
  original = collections.defaultdict(list)
  for key_value_pair in original_metadata:
    key, value = tuple(key_value_pair)
    original[key].append(value)
  transmitted = collections.defaultdict(list)
  for key_value_pair in transmitted_metadata:
    key, value = tuple(key_value_pair)
    transmitted[key].append(value)

  for key, values in six.iteritems(original):
    transmitted_values = transmitted[key]
    transmitted_iterator = iter(transmitted_values)
    try:
      for value in values:
        while True:
          transmitted_value = next(transmitted_iterator)
          if value == transmitted_value:
            break
    except StopIteration:
      return False
  else:
    return True