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: submit_observations.rs
    path of file: ./repos/wormhole/cosmwasm/contracts/global-accountant/tests
    
    the code of the file until where you have to start completion: mod helpers;

use std::collections::BTreeMap;

use accountant::state::{account, transfer, Kind, Modification, TokenAddress};
use cosmwasm_std::{from_binary, to_binary, Binary, Event, Uint256};
    
fn missing_guardian_set() {
    let (wh, mut contract) = proper_instantiate();
    let index = wh.guardian_set_index();
    let num_guardians = wh.num_guardians();

    let emitter_chain = 2;
    let amount = Amount(Uint256::from(500u128).to_be_bytes());
    let token_address = Address([0xccu8; 32]);
    let token_chain = 2.into();
    let recipient_chain = 14.into();

    let key = transfer::Key::new(emitter_chain, [emitter_chain as u8; 32].into(), 37);
    let msg = Message::Transfer {
        amount,
        token_address,
        token_chain,
        recipient: Address([0xb9u8; 32]),
        recipient_chain,
        fee: Amount([0u8; 32]),
    };

    let err = transfer_tokens(&wh, &mut contract, key, msg, index + 1, num_guardians)
        .expect_err("successfully submitted observations with invalid guardian set");
    assert_eq!(
        "generic error: querier contract error: invalid guardian set",
        err.root_cause().to_string().to_lowercase()
    );
}