def METHOD_NAME(backend: str) -> Tuple[DataFrame, DataFrame]:
    """Returns test data for the given backend."""
    data_df = pd.DataFrame(pd.Series([2, 4, 6, 8, 10]), columns=["x"])
    proc_df = pd.DataFrame(columns=["x"])
    if backend == "ray":
        import dask.dataframe as dd
        data_df = dd.from_pandas(data_df, npartitions=1).reset_index()
        proc_df = dd.from_pandas(proc_df, npartitions=1).reset_index()
    return data_df, proc_df