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: purge_chain_works.rs
    path of file: ./repos/polkadot/tests
    
    the code of the file until where you have to start completion: // Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Substrate is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GN
    
async fn purge_chain_rocksdb_works() {
	use nix::{
		sys::signal::{kill, Signal::SIGINT},
		unistd::Pid,
	};

	let tmpdir = tempdir().expect("could not create temp dir");

	let mut cmd = Command::new(cargo_bin("polkadot"))
		.stdout(process::Stdio::piped())
		.stderr(process::Stdio::piped())
		.args(["--dev", "-d"])
		.arg(tmpdir.path())
		.arg("--port")
		.arg("33034")
		.arg("--no-hardware-benchmarks")
		.spawn()
		.unwrap();

	let (ws_url, _) = common::find_ws_url_from_output(cmd.stderr.take().unwrap());

	// Let it produce 1 block.
	common::wait_n_finalized_blocks(1, Duration::from_secs(60), &ws_url)
		.await
		.unwrap();

	// Send SIGINT to node.
	kill(Pid::from_raw(cmd.id().try_into().unwrap()), SIGINT).unwrap();
	// Wait for the node to handle it and exit.
	assert!(common::wait_for(&mut cmd, 30).map(|x| x.success()).unwrap_or_default());
	assert!(tmpdir.path().join("chains/polkadot_dev").exists());
	assert!(tmpdir.path().join("chains/polkadot_dev/db/full").exists());
	assert!(tmpdir.path().join("chains/polkadot_dev/db/full/parachains").exists());

	// Purge chain
	let status = Command::new(cargo_bin("polkadot"))
		.args(["purge-chain", "--dev", "-d"])
		.arg(tmpdir.path())
		.arg("-y")
		.status()
		.unwrap();
	assert!(status.success());

	// Make sure that the chain folder exists, but `db/full` is deleted.
	assert!(tmpdir.path().join("chains/polkadot_dev").exists());
	assert!(!tmpdir.path().join("chains/polkadot_dev/db/full").exists());
}