"""Various utility functions for testing."""
import gzip
from pathlib import Path


def load_gpx_asset(filename):
    """Load a GPX test asset.

    This looks in the tests/assets/ folder, reads and unzips the file and
    returns its contents.

    :param filename: Name of the asset to load.
    :type filename: str
    :return: The content of the asset as bytes.
    :rtype: bytes
    """
    asset_dir = Path(__file__).parent / 'assets'
    test_file = asset_dir / filename
    with gzip.open(test_file, 'rb') as fobj:
        return fobj.read()