def METHOD_NAME(package_command, first_app):
    """An unknown packaging format raises an error."""
    first_app.target_vendor_base = None
    first_app.packaging_format = "system"
    with pytest.raises(
        BriefcaseCommandError,
        match=r"Briefcase doesn't know the system packaging format for somevendor.",
    ):
        package_command.verify_app_tools(first_app)