How to use the barman.infofile.Field function in barman

def test_field_dump_decorator(self):
        test_field = Field('test_field')
        dump_function = str
        test_field = test_field.dump(dump_function)
        assert test_field.to_str == dump_function

    def test_field_load_decorator(self):
        test_field = Field('test_field')
        load_function = int
        test_field = test_field.dump(load_function)
        assert test_field.to_str == load_function


class DummyFieldListFile(FieldListFile):
    dummy = Field('dummy', dump=str, load=int, default=12, doc='dummy_field')


# noinspection PyMethodMayBeStatic
class TestFieldListFile(object):
    def test_field_list_file_creation(self):
        with pytest.raises(AttributeError):
            FieldListFile(test_argument=11)

        field = FieldListFile()
        assert field

    def test_subclass_creation(self):
        with pytest.raises(AttributeError):
            DummyFieldListFile(test_argument=11)

        field = DummyFieldListFile()

def test_field_load_decorator(self):
        test_field = Field('test_field')
        load_function = int
        test_field = test_field.dump(load_function)
        assert test_field.to_str == load_function

def test_field_creation(self):
        field = Field('test_field')
        assert field

yield (name, value)

    def __repr__(self):
        return "%s(%s)" % (
            self.__class__.__name__,
            ', '.join(['%s=%r' % x for x in self.items()]))


class WalFileInfo(FieldListFile):
    """
    Metadata of a WAL file.
    """

    __slots__ = ('orig_filename',)

    name = Field('name', doc='base name of WAL file')
    size = Field('size', load=int, doc='WAL file size after compression')
    time = Field('time', load=float, doc='WAL file modification time '
                                         '(seconds since epoch)')
    compression = Field('compression', doc='compression type')

    @classmethod
    def from_file(cls, filename, unidentified_compression=None, **kwargs):
        """
        Factory method to generate a WalFileInfo from a WAL file.

        Every keyword argument will override any attribute from the provided
        file. If a keyword argument doesn't has a corresponding attribute
        an AttributeError exception is raised.

        :param str filename: the file to inspect
        :param str unidentified_compression: the compression to set if

timeline = Field('timeline', load=int)
    begin_time = Field('begin_time', load=load_datetime_tz)
    begin_xlog = Field('begin_xlog')
    begin_wal = Field('begin_wal')
    begin_offset = Field('begin_offset', load=int)
    size = Field('size', load=int)
    deduplicated_size = Field('deduplicated_size', load=int)
    end_time = Field('end_time', load=load_datetime_tz)
    end_xlog = Field('end_xlog')
    end_wal = Field('end_wal')
    end_offset = Field('end_offset', load=int)
    status = Field('status', default=EMPTY)
    server_name = Field('server_name')
    error = Field('error')
    mode = Field('mode')
    config_file = Field('config_file')
    hba_file = Field('hba_file')
    ident_file = Field('ident_file')
    included_files = Field('included_files',
                           load=ast.literal_eval, dump=null_repr)
    backup_label = Field('backup_label', load=ast.literal_eval, dump=null_repr)
    copy_stats = Field('copy_stats', load=ast.literal_eval, dump=null_repr)
    xlog_segment_size = Field('xlog_segment_size', load=int,
                              default=xlog.DEFAULT_XLOG_SEG_SIZE)
    systemid = Field('systemid')

    __slots__ = 'backup_id', 'backup_version'

    def __init__(self, backup_id, **kwargs):
        """
        Stores meta information about a single backup

# Timeline is an integer
    timeline = Field('timeline', load=int)
    begin_time = Field('begin_time', load=load_datetime_tz)
    begin_xlog = Field('begin_xlog')
    begin_wal = Field('begin_wal')
    begin_offset = Field('begin_offset', load=int)
    size = Field('size', load=int)
    deduplicated_size = Field('deduplicated_size', load=int)
    end_time = Field('end_time', load=load_datetime_tz)
    end_xlog = Field('end_xlog')
    end_wal = Field('end_wal')
    end_offset = Field('end_offset', load=int)
    status = Field('status', default=EMPTY)
    server_name = Field('server_name')
    error = Field('error')
    mode = Field('mode')
    config_file = Field('config_file')
    hba_file = Field('hba_file')
    ident_file = Field('ident_file')
    included_files = Field('included_files',
                           load=ast.literal_eval, dump=null_repr)
    backup_label = Field('backup_label', load=ast.literal_eval, dump=null_repr)
    copy_stats = Field('copy_stats', load=ast.literal_eval, dump=null_repr)
    xlog_segment_size = Field('xlog_segment_size', load=int,
                              default=xlog.DEFAULT_XLOG_SEG_SIZE)
    systemid = Field('systemid')

    __slots__ = 'backup_id', 'backup_version'

    def __init__(self, backup_id, **kwargs):
        """
        Stores meta information about a single backup

POTENTIALLY_OBSOLETE = 'OBSOLETE*'
    NONE = '-'
    RETENTION_STATUS = (OBSOLETE, VALID, POTENTIALLY_OBSOLETE, NONE)

    version = Field('version', load=int)
    pgdata = Field('pgdata')
    # Parse the tablespaces as a literal Python list of namedtuple
    # Output the tablespaces as a literal Python list of tuple
    tablespaces = Field('tablespaces', load=load_tablespace_list,
                        dump=output_tablespace_list)
    # Timeline is an integer
    timeline = Field('timeline', load=int)
    begin_time = Field('begin_time', load=load_datetime_tz)
    begin_xlog = Field('begin_xlog')
    begin_wal = Field('begin_wal')
    begin_offset = Field('begin_offset', load=int)
    size = Field('size', load=int)
    deduplicated_size = Field('deduplicated_size', load=int)
    end_time = Field('end_time', load=load_datetime_tz)
    end_xlog = Field('end_xlog')
    end_wal = Field('end_wal')
    end_offset = Field('end_offset', load=int)
    status = Field('status', default=EMPTY)
    server_name = Field('server_name')
    error = Field('error')
    mode = Field('mode')
    config_file = Field('config_file')
    hba_file = Field('hba_file')
    ident_file = Field('ident_file')
    included_files = Field('included_files',
                           load=ast.literal_eval, dump=null_repr)
    backup_label = Field('backup_label', load=ast.literal_eval, dump=null_repr)

# Output the tablespaces as a literal Python list of tuple
    tablespaces = Field('tablespaces', load=load_tablespace_list,
                        dump=output_tablespace_list)
    # Timeline is an integer
    timeline = Field('timeline', load=int)
    begin_time = Field('begin_time', load=load_datetime_tz)
    begin_xlog = Field('begin_xlog')
    begin_wal = Field('begin_wal')
    begin_offset = Field('begin_offset', load=int)
    size = Field('size', load=int)
    deduplicated_size = Field('deduplicated_size', load=int)
    end_time = Field('end_time', load=load_datetime_tz)
    end_xlog = Field('end_xlog')
    end_wal = Field('end_wal')
    end_offset = Field('end_offset', load=int)
    status = Field('status', default=EMPTY)
    server_name = Field('server_name')
    error = Field('error')
    mode = Field('mode')
    config_file = Field('config_file')
    hba_file = Field('hba_file')
    ident_file = Field('ident_file')
    included_files = Field('included_files',
                           load=ast.literal_eval, dump=null_repr)
    backup_label = Field('backup_label', load=ast.literal_eval, dump=null_repr)
    copy_stats = Field('copy_stats', load=ast.literal_eval, dump=null_repr)
    xlog_segment_size = Field('xlog_segment_size', load=int,
                              default=xlog.DEFAULT_XLOG_SEG_SIZE)
    systemid = Field('systemid')

    __slots__ = 'backup_id', 'backup_version'

WAITING_FOR_WALS = 'WAITING_FOR_WALS'
    DONE = 'DONE'
    SYNCING = 'SYNCING'
    STATUS_COPY_DONE = (WAITING_FOR_WALS, DONE)
    STATUS_ALL = (EMPTY, STARTED, WAITING_FOR_WALS, DONE, SYNCING, FAILED)
    STATUS_NOT_EMPTY = (STARTED, WAITING_FOR_WALS, DONE, SYNCING, FAILED)
    STATUS_ARCHIVING = (STARTED, WAITING_FOR_WALS, DONE, SYNCING)

    #: Status according to retention policies
    OBSOLETE = 'OBSOLETE'
    VALID = 'VALID'
    POTENTIALLY_OBSOLETE = 'OBSOLETE*'
    NONE = '-'
    RETENTION_STATUS = (OBSOLETE, VALID, POTENTIALLY_OBSOLETE, NONE)

    version = Field('version', load=int)
    pgdata = Field('pgdata')
    # Parse the tablespaces as a literal Python list of namedtuple
    # Output the tablespaces as a literal Python list of tuple
    tablespaces = Field('tablespaces', load=load_tablespace_list,
                        dump=output_tablespace_list)
    # Timeline is an integer
    timeline = Field('timeline', load=int)
    begin_time = Field('begin_time', load=load_datetime_tz)
    begin_xlog = Field('begin_xlog')
    begin_wal = Field('begin_wal')
    begin_offset = Field('begin_offset', load=int)
    size = Field('size', load=int)
    deduplicated_size = Field('deduplicated_size', load=int)
    end_time = Field('end_time', load=load_datetime_tz)
    end_xlog = Field('end_xlog')
    end_wal = Field('end_wal')

end_time = Field('end_time', load=load_datetime_tz)
    end_xlog = Field('end_xlog')
    end_wal = Field('end_wal')
    end_offset = Field('end_offset', load=int)
    status = Field('status', default=EMPTY)
    server_name = Field('server_name')
    error = Field('error')
    mode = Field('mode')
    config_file = Field('config_file')
    hba_file = Field('hba_file')
    ident_file = Field('ident_file')
    included_files = Field('included_files',
                           load=ast.literal_eval, dump=null_repr)
    backup_label = Field('backup_label', load=ast.literal_eval, dump=null_repr)
    copy_stats = Field('copy_stats', load=ast.literal_eval, dump=null_repr)
    xlog_segment_size = Field('xlog_segment_size', load=int,
                              default=xlog.DEFAULT_XLOG_SEG_SIZE)
    systemid = Field('systemid')

    __slots__ = 'backup_id', 'backup_version'

    def __init__(self, backup_id, **kwargs):
        """
        Stores meta information about a single backup

        :param str,None backup_id:
        """
        self.backup_version = 2
        self.backup_id = backup_id
        super(BackupInfo, self).__init__(**kwargs)

    def get_required_wal_segments(self):