def METHOD_NAME(
    self,
    expected: Optional[str],
    repo: Optional[str],
    tag: Optional[str],
    tmp_path: Path,
) -> None:
    """Test _set_docker."""
    assert (
        ImageBuildArgs.parse_obj(
            {
                "docker": {"tag": tag} if tag else {},
                "path": tmp_path,
                "repo": repo,
            }
        ).docker.tag
        == expected
    )