Python google.protobuf.internal.api_implementation.Type() Examples

def testClear(self):
    proto = unittest_pb2.TestAllTypes()
    # C++ implementation does not support lazy fields right now so leave it
    # out for now.
    if api_implementation.Type() == 'python':
      test_util.SetAllFields(proto)
    else:
      test_util.SetAllNonLazyFields(proto)
    # Clear the message.
    proto.Clear()
    self.assertEqual(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllTypes()
    self.assertEqual(proto, empty_proto)

    # Test if extensions which were set are cleared.
    proto = unittest_pb2.TestAllExtensions()
    test_util.SetAllExtensions(proto)
    # Clear the message.
    proto.Clear()
    self.assertEqual(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllExtensions()
    self.assertEqual(proto, empty_proto) 

def testClear(self):
    proto = unittest_pb2.TestAllTypes()
    # C++ implementation does not support lazy fields right now so leave it
    # out for now.
    if api_implementation.Type() == 'python':
      test_util.SetAllFields(proto)
    else:
      test_util.SetAllNonLazyFields(proto)
    # Clear the message.
    proto.Clear()
    self.assertEqual(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllTypes()
    self.assertEqual(proto, empty_proto)

    # Test if extensions which were set are cleared.
    proto = unittest_pb2.TestAllExtensions()
    test_util.SetAllExtensions(proto)
    # Clear the message.
    proto.Clear()
    self.assertEqual(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllExtensions()
    self.assertEqual(proto, empty_proto) 

def testFindTypeErrors(self):
    self.assertRaises(TypeError, self.pool.FindExtensionByNumber, '')

    # TODO(jieluo): Fix python to raise correct errors.
    if api_implementation.Type() == 'cpp':
      self.assertRaises(TypeError, self.pool.FindMethodByName, 0)
      self.assertRaises(KeyError, self.pool.FindMethodByName, '')
      error_type = TypeError
    else:
      error_type = AttributeError
    self.assertRaises(error_type, self.pool.FindMessageTypeByName, 0)
    self.assertRaises(error_type, self.pool.FindFieldByName, 0)
    self.assertRaises(error_type, self.pool.FindExtensionByName, 0)
    self.assertRaises(error_type, self.pool.FindEnumTypeByName, 0)
    self.assertRaises(error_type, self.pool.FindOneofByName, 0)
    self.assertRaises(error_type, self.pool.FindServiceByName, 0)
    self.assertRaises(error_type, self.pool.FindFileContainingSymbol, 0)
    if api_implementation.Type() == 'python':
      error_type = KeyError
    self.assertRaises(error_type, self.pool.FindFileByName, 0) 

def testFindExtensionByName(self):
    if isinstance(self, SecondaryDescriptorFromDescriptorDB):
      if api_implementation.Type() == 'cpp':
        # TODO(jieluo): Fix cpp extension to find extension correctly
        # when descriptor pool is using an underlying database.
        return
    # An extension defined in a message.
    extension = self.pool.FindExtensionByName(
        'google.protobuf.python.internal.Factory2Message.one_more_field')
    self.assertEqual(extension.name, 'one_more_field')
    # An extension defined at file scope.
    extension = self.pool.FindExtensionByName(
        'google.protobuf.python.internal.another_field')
    self.assertEqual(extension.name, 'another_field')
    self.assertEqual(extension.number, 1002)
    with self.assertRaises(KeyError):
      self.pool.FindFieldByName('Does not exist') 

def testComplexNesting(self):
    if isinstance(self, SecondaryDescriptorFromDescriptorDB):
      if api_implementation.Type() == 'cpp':
        # Cpp extension cannot call Add on a DescriptorPool
        # that uses a DescriptorDatabase.
        # TODO(jieluo): Fix python and cpp extension diff.
        return
    more_messages_desc = descriptor_pb2.FileDescriptorProto.FromString(
        more_messages_pb2.DESCRIPTOR.serialized_pb)
    test1_desc = descriptor_pb2.FileDescriptorProto.FromString(
        descriptor_pool_test1_pb2.DESCRIPTOR.serialized_pb)
    test2_desc = descriptor_pb2.FileDescriptorProto.FromString(
        descriptor_pool_test2_pb2.DESCRIPTOR.serialized_pb)
    self.pool.Add(more_messages_desc)
    self.pool.Add(test1_desc)
    self.pool.Add(test2_desc)
    TEST1_FILE.CheckFile(self, self.pool)
    TEST2_FILE.CheckFile(self, self.pool) 

def CheckField(self, test, msg_desc, name, index, file_desc):
    field_desc = msg_desc.fields_by_name[name]
    field_type_desc = msg_desc.nested_types_by_name[self.type_name]
    test.assertEqual(name, field_desc.name)
    expected_field_full_name = '.'.join([msg_desc.full_name, name])
    test.assertEqual(expected_field_full_name, field_desc.full_name)
    test.assertEqual(index, field_desc.index)
    test.assertEqual(self.number, field_desc.number)
    test.assertEqual(descriptor.FieldDescriptor.TYPE_MESSAGE, field_desc.type)
    test.assertEqual(descriptor.FieldDescriptor.CPPTYPE_MESSAGE,
                     field_desc.cpp_type)
    test.assertFalse(field_desc.has_default_value)
    test.assertEqual(msg_desc, field_desc.containing_type)
    test.assertEqual(field_type_desc, field_desc.message_type)
    test.assertEqual(file_desc, field_desc.file)
    # TODO(jieluo): Fix python and cpp extension diff for message field
    # default value.
    if api_implementation.Type() == 'cpp':
      test.assertRaises(
          NotImplementedError, getattr, field_desc, 'default_value') 

def testParseErrors(self, message_module):
    msg = message_module.TestAllTypes()
    self.assertRaises(TypeError, msg.FromString, 0)
    self.assertRaises(Exception, msg.FromString, '0')
    # TODO(jieluo): Fix cpp extension to raise error instead of warning.
    # b/27494216
    end_tag = encoder.TagBytes(1, 4)
    if api_implementation.Type() == 'python':
      with self.assertRaises(message.DecodeError) as context:
        msg.FromString(end_tag)
      self.assertEqual('Unexpected end-group tag.', str(context.exception))
    else:
      with warnings.catch_warnings(record=True) as w:
        # Cause all warnings to always be triggered.
        warnings.simplefilter('always')
        msg.FromString(end_tag)
        assert len(w) == 1
        assert issubclass(w[-1].category, RuntimeWarning)
        self.assertEqual('Unexpected end-group tag: Not all data was converted',
                         str(w[-1].message)) 

def testSetRepeatedComposite(self, message_module):
    m = message_module.TestAllTypes()
    with self.assertRaises(AttributeError):
      m.repeated_int32 = []
    m.repeated_int32.append(1)
    if api_implementation.Type() == 'cpp':
      # For test coverage: cpp has a different path if composite
      # field is in cache
      with self.assertRaises(TypeError):
        m.repeated_int32 = []
    else:
      with self.assertRaises(AttributeError):
        m.repeated_int32 = []


# Class to test proto2-only features (required, extensions, etc.) 

def CheckFieldDescriptor(self, field_descriptor):
    # Basic properties
    self.assertEqual(field_descriptor.name, 'optional_int32')
    self.assertEqual(field_descriptor.camelcase_name, 'optionalInt32')
    self.assertEqual(field_descriptor.full_name,
                     'protobuf_unittest.TestAllTypes.optional_int32')
    self.assertEqual(field_descriptor.containing_type.name, 'TestAllTypes')
    self.assertEqual(field_descriptor.file, unittest_pb2.DESCRIPTOR)
    # Test equality and hashability
    self.assertEqual(field_descriptor, field_descriptor)
    self.assertEqual(
        field_descriptor.containing_type.fields_by_name['optional_int32'],
        field_descriptor)
    self.assertEqual(
        field_descriptor.containing_type.fields_by_camelcase_name[
            'optionalInt32'],
        field_descriptor)
    self.assertIn(field_descriptor, [field_descriptor])
    self.assertIn(field_descriptor, {field_descriptor: None})
    self.assertEqual(None, field_descriptor.extension_scope)
    self.assertEqual(None, field_descriptor.enum_type)
    if api_implementation.Type() == 'cpp':
      # For test coverage only
      self.assertEqual(field_descriptor.id, field_descriptor.id) 

def ProtoTypeToCppProtoType(proto_type):
    """Converts from a Python proto type to a C++ Proto Type.

    The Python ProtocolBuffer classes specify both the 'Python' datatype and the
    'C++' datatype - and they're not the same. This helper method should
    translate from one to another.

    Args:
      proto_type: the Python proto type (descriptor.FieldDescriptor.TYPE_*)
    Returns:
      descriptor.FieldDescriptor.CPPTYPE_*, the C++ type.
    Raises:
      TypeTransformationError: when the Python proto type isn't known.
    """
    try:
      return FieldDescriptor._PYTHON_TO_CPP_PROTO_TYPE_MAP[proto_type]
    except KeyError:
      raise TypeTransformationError('Unknown proto_type: %s' % proto_type) 

def __init__(self, name, package, options=None, serialized_pb=None,
               dependencies=None, public_dependencies=None,
               syntax=None, pool=None):
    """Constructor."""
    super(FileDescriptor, self).__init__(options, 'FileOptions')

    if pool is None:
      from google.protobuf import descriptor_pool
      pool = descriptor_pool.Default()
    self.pool = pool
    self.message_types_by_name = {}
    self.name = name
    self.package = package
    self.syntax = syntax or "proto2"
    self.serialized_pb = serialized_pb

    self.enum_types_by_name = {}
    self.extensions_by_name = {}
    self.services_by_name = {}
    self.dependencies = (dependencies or [])
    self.public_dependencies = (public_dependencies or [])

    if (api_implementation.Type() == 'cpp' and
        self.serialized_pb is not None):
      _message.default_pool.AddSerializedFile(self.serialized_pb) 

def testClear(self):
    proto = unittest_pb2.TestAllTypes()
    # C++ implementation does not support lazy fields right now so leave it
    # out for now.
    if api_implementation.Type() == 'python':
      test_util.SetAllFields(proto)
    else:
      test_util.SetAllNonLazyFields(proto)
    # Clear the message.
    proto.Clear()
    self.assertEqual(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllTypes()
    self.assertEqual(proto, empty_proto)

    # Test if extensions which were set are cleared.
    proto = unittest_pb2.TestAllExtensions()
    test_util.SetAllExtensions(proto)
    # Clear the message.
    proto.Clear()
    self.assertEqual(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllExtensions()
    self.assertEqual(proto, empty_proto) 

def ProtoTypeToCppProtoType(proto_type):
    """Converts from a Python proto type to a C++ Proto Type.

    The Python ProtocolBuffer classes specify both the 'Python' datatype and the
    'C++' datatype - and they're not the same. This helper method should
    translate from one to another.

    Args:
      proto_type: the Python proto type (descriptor.FieldDescriptor.TYPE_*)
    Returns:
      descriptor.FieldDescriptor.CPPTYPE_*, the C++ type.
    Raises:
      TypeTransformationError: when the Python proto type isn't known.
    """
    try:
      return FieldDescriptor._PYTHON_TO_CPP_PROTO_TYPE_MAP[proto_type]
    except KeyError:
      raise TypeTransformationError('Unknown proto_type: %s' % proto_type) 

def ProtoTypeToCppProtoType(proto_type):
    """Converts from a Python proto type to a C++ Proto Type.

    The Python ProtocolBuffer classes specify both the 'Python' datatype and the
    'C++' datatype - and they're not the same. This helper method should
    translate from one to another.

    Args:
      proto_type: the Python proto type (descriptor.FieldDescriptor.TYPE_*)
    Returns:
      descriptor.FieldDescriptor.CPPTYPE_*, the C++ type.
    Raises:
      TypeTransformationError: when the Python proto type isn't known.
    """
    try:
      return FieldDescriptor._PYTHON_TO_CPP_PROTO_TYPE_MAP[proto_type]
    except KeyError:
      raise TypeTransformationError('Unknown proto_type: %s' % proto_type) 

def __init__(self, name, package, options=None, serialized_pb=None,
               dependencies=None, public_dependencies=None,
               syntax=None, pool=None):
    """Constructor."""
    super(FileDescriptor, self).__init__(options, 'FileOptions')

    if pool is None:
      from google.protobuf import descriptor_pool
      pool = descriptor_pool.Default()
    self.pool = pool
    self.message_types_by_name = {}
    self.name = name
    self.package = package
    self.syntax = syntax or "proto2"
    self.serialized_pb = serialized_pb

    self.enum_types_by_name = {}
    self.extensions_by_name = {}
    self.services_by_name = {}
    self.dependencies = (dependencies or [])
    self.public_dependencies = (public_dependencies or [])

    if (api_implementation.Type() == 'cpp' and
        self.serialized_pb is not None):
      _message.default_pool.AddSerializedFile(self.serialized_pb) 

def ProtoTypeToCppProtoType(proto_type):
    """Converts from a Python proto type to a C++ Proto Type.

    The Python ProtocolBuffer classes specify both the 'Python' datatype and the
    'C++' datatype - and they're not the same. This helper method should
    translate from one to another.

    Args:
      proto_type: the Python proto type (descriptor.FieldDescriptor.TYPE_*)
    Returns:
      descriptor.FieldDescriptor.CPPTYPE_*, the C++ type.
    Raises:
      TypeTransformationError: when the Python proto type isn't known.
    """
    try:
      return FieldDescriptor._PYTHON_TO_CPP_PROTO_TYPE_MAP[proto_type]
    except KeyError:
      raise TypeTransformationError('Unknown proto_type: %s' % proto_type) 

def testClear(self):
    proto = unittest_pb2.TestAllTypes()
    # C++ implementation does not support lazy fields right now so leave it
    # out for now.
    if api_implementation.Type() == 'python':
      test_util.SetAllFields(proto)
    else:
      test_util.SetAllNonLazyFields(proto)
    # Clear the message.
    proto.Clear()
    self.assertEquals(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllTypes()
    self.assertEquals(proto, empty_proto)

    # Test if extensions which were set are cleared.
    proto = unittest_pb2.TestAllExtensions()
    test_util.SetAllExtensions(proto)
    # Clear the message.
    proto.Clear()
    self.assertEquals(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllExtensions()
    self.assertEquals(proto, empty_proto) 

def __init__(self, name, package, options=None, serialized_pb=None,
               dependencies=None):
    """Constructor."""
    super(FileDescriptor, self).__init__(options, 'FileOptions')

    self.message_types_by_name = {}
    self.name = name
    self.package = package
    self.serialized_pb = serialized_pb

    self.enum_types_by_name = {}
    self.extensions_by_name = {}
    self.dependencies = (dependencies or [])

    if (api_implementation.Type() == 'cpp' and
        self.serialized_pb is not None):
      if api_implementation.Version() == 2:
        # pylint: disable=protected-access
        _message.Message._BuildFile(self.serialized_pb)
        # pylint: enable=protected-access
      else:
        cpp_message.BuildFile(self.serialized_pb) 

def ProtoTypeToCppProtoType(proto_type):
    """Converts from a Python proto type to a C++ Proto Type.

    The Python ProtocolBuffer classes specify both the 'Python' datatype and the
    'C++' datatype - and they're not the same. This helper method should
    translate from one to another.

    Args:
      proto_type: the Python proto type (descriptor.FieldDescriptor.TYPE_*)
    Returns:
      descriptor.FieldDescriptor.CPPTYPE_*, the C++ type.
    Raises:
      TypeTransformationError: when the Python proto type isn't known.
    """
    try:
      return FieldDescriptor._PYTHON_TO_CPP_PROTO_TYPE_MAP[proto_type]
    except KeyError:
      raise TypeTransformationError('Unknown proto_type: %s' % proto_type) 

def setUp(self):
    self.descriptor = missing_enum_values_pb2.TestEnumValues.DESCRIPTOR

    self.message = missing_enum_values_pb2.TestEnumValues()
    self.message.optional_nested_enum = (
      missing_enum_values_pb2.TestEnumValues.ZERO)
    self.message.repeated_nested_enum.extend([
      missing_enum_values_pb2.TestEnumValues.ZERO,
      missing_enum_values_pb2.TestEnumValues.ONE,
      ])
    self.message.packed_nested_enum.extend([
      missing_enum_values_pb2.TestEnumValues.ZERO,
      missing_enum_values_pb2.TestEnumValues.ONE,
      ])
    self.message_data = self.message.SerializeToString()
    self.missing_message = missing_enum_values_pb2.TestMissingEnumValues()
    self.missing_message.ParseFromString(self.message_data)
    if api_implementation.Type() != 'cpp':
      # _unknown_fields is an implementation detail.
      self.unknown_fields = self.missing_message._unknown_fields

  # All the tests that use GetField() check an implementation detail of the
  # Python implementation, which stores unknown fields as serialized strings.
  # These tests are skipped by the C++ implementation: it's enough to check that
  # the message is correctly serialized. 

def testParsingFlatClassWithExplicitClassDeclaration(self):
    """Test that the generated class can parse a flat message."""
    # TODO(xiaofeng): This test fails with cpp implemetnation in the call
    # of six.with_metaclass(). The other two callsites of with_metaclass
    # in this file are both excluded from cpp test, so it might be expected
    # to fail. Need someone more familiar with the python code to take a
    # look at this.
    if api_implementation.Type() != 'python':
      return
    file_descriptor = descriptor_pb2.FileDescriptorProto()
    file_descriptor.ParseFromString(self._GetSerializedFileDescriptor('A'))
    msg_descriptor = descriptor.MakeDescriptor(
        file_descriptor.message_type[0])

    class MessageClass(six.with_metaclass(reflection.GeneratedProtocolMessageType, message.Message)):
      DESCRIPTOR = msg_descriptor
    msg = MessageClass()
    msg_str = (
        'flat: 0 '
        'flat: 1 '
        'flat: 2 ')
    text_format.Merge(msg_str, msg)
    self.assertEqual(msg.flat, [0, 1, 2]) 

def testClear(self):
    proto = unittest_pb2.TestAllTypes()
    # C++ implementation does not support lazy fields right now so leave it
    # out for now.
    if api_implementation.Type() == 'python':
      test_util.SetAllFields(proto)
    else:
      test_util.SetAllNonLazyFields(proto)
    # Clear the message.
    proto.Clear()
    self.assertEqual(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllTypes()
    self.assertEqual(proto, empty_proto)

    # Test if extensions which were set are cleared.
    proto = unittest_pb2.TestAllExtensions()
    test_util.SetAllExtensions(proto)
    # Clear the message.
    proto.Clear()
    self.assertEqual(proto.ByteSize(), 0)
    empty_proto = unittest_pb2.TestAllExtensions()
    self.assertEqual(proto, empty_proto) 

def __init__(self, name, package, options=None, serialized_pb=None,
               dependencies=None, syntax=None):
    """Constructor."""
    super(FileDescriptor, self).__init__(options, 'FileOptions')

    self.message_types_by_name = {}
    self.name = name
    self.package = package
    self.syntax = syntax or "proto2"
    self.serialized_pb = serialized_pb

    self.enum_types_by_name = {}
    self.extensions_by_name = {}
    self.dependencies = (dependencies or [])

    if (api_implementation.Type() == 'cpp' and
        self.serialized_pb is not None):
      _message.default_pool.AddSerializedFile(self.serialized_pb) 

def testParsingFlatClassWithExplicitClassDeclaration(self):
    """Test that the generated class can parse a flat message."""
    # TODO(xiaofeng): This test fails with cpp implemetnation in the call
    # of six.with_metaclass(). The other two callsites of with_metaclass
    # in this file are both excluded from cpp test, so it might be expected
    # to fail. Need someone more familiar with the python code to take a
    # look at this.
    if api_implementation.Type() != 'python':
      return
    file_descriptor = descriptor_pb2.FileDescriptorProto()
    file_descriptor.ParseFromString(self._GetSerializedFileDescriptor('A'))
    msg_descriptor = descriptor.MakeDescriptor(
        file_descriptor.message_type[0])

    class MessageClass(six.with_metaclass(reflection.GeneratedProtocolMessageType, message.Message)):
      DESCRIPTOR = msg_descriptor
    msg = MessageClass()
    msg_str = (
        'flat: 0 '
        'flat: 1 '
        'flat: 2 ')
    text_format.Merge(msg_str, msg)
    self.assertEqual(msg.flat, [0, 1, 2]) 

def testImplementationSetting(self):
    self.assertEqual('python', api_implementation.Type()) 

def testCopyFromBadType(self):
    # The python implementation doesn't raise an exception in this
    # case. In theory it should.
    if api_implementation.Type() == 'python':
      return
    proto1 = unittest_pb2.TestAllTypes()
    proto2 = unittest_pb2.TestAllExtensions()
    self.assertRaises(TypeError, proto1.CopyFrom, proto2) 

def testAddSerializedFile(self):
    if isinstance(self, SecondaryDescriptorFromDescriptorDB):
      if api_implementation.Type() == 'cpp':
        # Cpp extension cannot call Add on a DescriptorPool
        # that uses a DescriptorDatabase.
        # TODO(jieluo): Fix python and cpp extension diff.
        return
    self.pool = descriptor_pool.DescriptorPool()
    self.pool.AddSerializedFile(self.factory_test1_fd.SerializeToString())
    self.pool.AddSerializedFile(self.factory_test2_fd.SerializeToString())
    self.testFindMessageTypeByName() 

def testEnumDefaultValue(self):
    """Test the default value of enums which don't start at zero."""
    def _CheckDefaultValue(file_descriptor):
      default_value = (file_descriptor
                       .message_types_by_name['DescriptorPoolTest1']
                       .fields_by_name['nested_enum']
                       .default_value)
      self.assertEqual(default_value,
                       descriptor_pool_test1_pb2.DescriptorPoolTest1.BETA)
    # First check what the generated descriptor contains.
    _CheckDefaultValue(descriptor_pool_test1_pb2.DESCRIPTOR)
    # Then check the generated pool. Normally this is the same descriptor.
    file_descriptor = symbol_database.Default().pool.FindFileByName(
        'google/protobuf/internal/descriptor_pool_test1.proto')
    self.assertIs(file_descriptor, descriptor_pool_test1_pb2.DESCRIPTOR)
    _CheckDefaultValue(file_descriptor)

    if isinstance(self, SecondaryDescriptorFromDescriptorDB):
      if api_implementation.Type() == 'cpp':
        # Cpp extension cannot call Add on a DescriptorPool
        # that uses a DescriptorDatabase.
        # TODO(jieluo): Fix python and cpp extension diff.
        return
    # Then check the dynamic pool and its internal DescriptorDatabase.
    descriptor_proto = descriptor_pb2.FileDescriptorProto.FromString(
        descriptor_pool_test1_pb2.DESCRIPTOR.serialized_pb)
    self.pool.Add(descriptor_proto)
    # And do the same check as above
    file_descriptor = self.pool.FindFileByName(
        'google/protobuf/internal/descriptor_pool_test1.proto')
    _CheckDefaultValue(file_descriptor) 

def setUp(self):
    self.descriptor = unittest_pb2.TestAllTypes.DESCRIPTOR
    self.all_fields = unittest_pb2.TestAllTypes()
    test_util.SetAllFields(self.all_fields)
    self.all_fields_data = self.all_fields.SerializeToString()
    self.empty_message = unittest_pb2.TestEmptyMessage()
    self.empty_message.ParseFromString(self.all_fields_data)
    if api_implementation.Type() != 'cpp':
      # _unknown_fields is an implementation detail.
      self.unknown_fields = self.empty_message._unknown_fields

  # All the tests that use GetField() check an implementation detail of the
  # Python implementation, which stores unknown fields as serialized strings.
  # These tests are skipped by the C++ implementation: it's enough to check that
  # the message is correctly serialized. 

def testParseTruncated(self):
    # This test is only applicable for the Python implementation of the API.
    if api_implementation.Type() != 'python':
      return

    first_proto = unittest_pb2.TestAllTypes()
    test_util.SetAllFields(first_proto)
    serialized = first_proto.SerializeToString()

    for truncation_point in range(len(serialized) + 1):
      try:
        second_proto = unittest_pb2.TestAllTypes()
        unknown_fields = unittest_pb2.TestEmptyMessage()
        pos = second_proto._InternalParse(serialized, 0, truncation_point)
        # If we didn't raise an error then we read exactly the amount expected.
        self.assertEqual(truncation_point, pos)

        # Parsing to unknown fields should not throw if parsing to known fields
        # did not.
        try:
          pos2 = unknown_fields._InternalParse(serialized, 0, truncation_point)
          self.assertEqual(truncation_point, pos2)
        except message.DecodeError:
          self.fail('Parsing unknown fields failed when parsing known fields '
                    'did not.')
      except message.DecodeError:
        # Parsing unknown fields should also fail.
        self.assertRaises(message.DecodeError, unknown_fields._InternalParse,
                          serialized, 0, truncation_point)