You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test_column_family.rs
    path of file: ./repos/rust-rocksdb/tests
    
    the code of the file until where you have to start completion: // Copyright 2020 Tyler Neely
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

mod util;

use pretty_assertions::assert_eq;

use rocksdb::{ColumnFamilyDescriptor, MergeOperands, Options, DB, DEFAULT_COLUMN_FAMILY_NAME};
use rocksdb::{TransactionDB, TransactionDBOptions};
use util::DBPath;

use std::fs;
use std::io;
use std::path::Path;

#[cfg(feature = "multi-threaded-cf")]
use rocksdb::MultiThreaded;
#[cfg(not(feature = "multi-threaded-cf"))]
use rocksdb::SingleThreaded;

fn dir_size(path: impl AsRef<Path>) -> io::Result<u64> {
    fn dir_size(mut dir: fs::ReadDir) -> io::Result<u64> {
        dir.try_fold(0, |acc, file| {
            let file = file?;
            let size = match file.metadata()? {
                data if data.is_dir() 
    
fn test_column_family_with_options() {
    let n = DBPath::new("_rust_rocksdb_cf_with_optionstest");
    {
        let mut cfopts = Options::default();
        cfopts.set_max_write_buffer_number(16);
        let cf_descriptor = ColumnFamilyDescriptor::new("cf1", cfopts);

        let mut opts = Options::default();
        opts.create_if_missing(true);
        opts.create_missing_column_families(true);

        let cfs = vec![cf_descriptor];
        match DB::open_cf_descriptors(&opts, &n, cfs) {
            Ok(_db) => println!("created db with column family descriptors successfully"),
            Err(e) => {
                panic!(
                    "could not create new database with column family descriptors: {}",
                    e
                );
            }
        }
    }

    {
        let mut cfopts = Options::default();
        cfopts.set_max_write_buffer_number(16);
        let cf_descriptor = ColumnFamilyDescriptor::new("cf1", cfopts);

        let opts = Options::default();
        let cfs = vec![cf_descriptor];

        match DB::open_cf_descriptors(&opts, &n, cfs) {
            Ok(_db) => println!("successfully re-opened database with column family descriptors"),
            Err(e) => {
                panic!(
                    "unable to re-open database with column family descriptors: {}",
                    e
                );
            }
        }
    }
}