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_conf_change.rs
    path of file: ./repos/tikv/components/raftstore-v2/tests/integrations
    
    the code of the file until where you have to start completion: // Copyright 2022 TiKV Project Authors. Licensed under Apache-2.0.

use std::{self, time::Duration};

use engine_traits::{Peekable, RaftEngineReadOnly, CF_DEFAULT};
use futures::executor::block_on;
use kvproto::{
    raft_cmdpb::{AdminCmdType, RaftCmdRequest},
    raft_serverpb::{PeerState, RaftM
    
fn remove_peer(cluster: &Cluster, offset_id: usize, region_id: u64, peer_id: u64) {
    let store_id = cluster.node(offset_id).id();
    let mut req = cluster.routers[0].new_request_for(region_id);
    let admin_req = req.mut_admin_request();
    admin_req.set_cmd_type(AdminCmdType::ChangePeer);
    admin_req
        .mut_change_peer()
        .set_change_type(ConfChangeType::RemoveNode);
    admin_req
        .mut_change_peer()
        .set_peer(new_learner_peer(store_id, peer_id));
    let resp = cluster.routers[0]
        .admin_command(region_id, req.clone())
        .unwrap();
    assert!(!resp.get_header().has_error(), "{:?}", resp);

    cluster.routers[offset_id]
        .send(region_id, PeerMsg::Tick(PeerTick::Raft))
        .unwrap();
    cluster.dispatch(region_id, vec![]);
    std::thread::sleep(Duration::from_millis(100));

    let raft_engine = &cluster.node(offset_id).running_state().unwrap().raft_engine;
    let region_state = raft_engine
        .get_region_state(region_id, u64::MAX)
        .unwrap()
        .unwrap();
    assert_eq!(region_state.get_state(), PeerState::Tombstone);
    assert_eq!(raft_engine.get_raft_state(region_id).unwrap(), None);
}