def merge_conda_files(files: List[Path], result_file: Path) -> None:
    """
    Merges the given Conda environment files using the conda_merge package, and writes the merged file to disk.
    :param files: The Conda environment files to read.
    :param result_file: The location where the merge results should be written.
    """
    # This code is a slightly modified version of conda_merge. That code can't be re-used easily
    # it defaults to writing to stdout
    env_definitions = [conda_merge.read_file(str(f)) for f in files]
    unified_definition = {}
    NAME = "name"
    CHANNELS = "channels"
    DEPENDENCIES = "dependencies"
    name = conda_merge.merge_names(env.get(NAME) for env in env_definitions)
    if name:
        unified_definition[NAME] = name
    try:
        channels = conda_merge.merge_channels(
            env.get(CHANNELS) for env in env_definitions)
    except conda_merge.MergeError:
        logging.error("Failed to merge channel priorities.")
        raise
    if channels:
        unified_definition[CHANNELS] = channels
    deps = conda_merge.merge_dependencies(
        env.get(DEPENDENCIES) for env in env_definitions)
    if deps:
        unified_definition[DEPENDENCIES] = deps
    with result_file.open("w") as f:
        ruamel.yaml.dump(unified_definition,
                         f,
                         indent=2,
                         default_flow_style=False)
def test_merge_names():
    """Should leave only the last name"""
    names = ['a', None, 'b', 'c', None, '']
    assert cm.merge_names(names) == 'c'
    assert cm.merge_names([]) is None
    assert cm.merge_names([None, None]) is None