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: uniswapv2_erc20.rs
    path of file: ./repos/solang/integration/subxt-tests/src/cases
    
    the code of the file until where you have to start completion: // SPDX-License-Identifier: Apache-2.0

use contract_transcode::ContractMessageTranscoder;
use hex::FromHex;

use parity_scale_codec::{Decode, DecodeAll, Encode, Input};
use rand::Rng;
use sp_core::{crypto::AccountId32, hexdisplay::AsBytesRef, keccak_256, U256};

use crate::{Contract, DeployContract, Execution, ReadContract, WriteContract, API};

#[tokio::test]
async fn setup() -> anyhow::Result<()> {
    let api = API::new().await?;

    let w = MockWorld::init(&api).await?;

    let rs = w
        .contract
        .try_call(&api, sp_keyring::AccountKeyring::Alice, 0, |t| {
            t.encode::<_, String>("name", [])
                .expect("unable to find selector")
        })
        .await
        .and_then(|v| String::decode(&mut &v[..]).map_err(Into::into))?;
    
async fn transfer() -> anyhow::Result<()> {
    let api = API::new().await?;

    let w = MockWorld::init(&api).await?;

    w.contract
        .call(&api, sp_keyring::AccountKeyring::Alice, 0, |_| {
            let mut sel = keccak_256(b"transfer(address,uint256)")[..4].to_vec();
            w.dave.encode_to(&mut sel);
            U256::from(10_u128.pow(18)).encode_to(&mut sel);
            sel
        })
        .await?;

    let alice_balance = w
        .contract
        .try_call(&api, sp_keyring::AccountKeyring::Alice, 0, |t| {
            t.encode::<_, String>("balanceOf", [format!("0x{}", hex::encode(&w.alice))])
                .expect("unable to find selector")
        })
        .await
        .and_then(|v| U256::decode(&mut &v[..]).map_err(Into::into))?;

    let dave_balance = w
        .contract
        .try_call(&api, sp_keyring::AccountKeyring::Alice, 0, |t| {
            t.encode::<_, String>("balanceOf", [format!("0x{}", hex::encode(&w.dave))])
                .expect("unable to find selector")
        })
        .await
        .and_then(|v| U256::decode(&mut &v[..]).map_err(Into::into))?;

    assert_eq!(
        alice_balance,
        U256::from_dec_str("10000")? * U256::from(10).pow(18_u8.into())
            - U256::from(10_u128.pow(18))
    );

    assert_eq!(dave_balance, U256::from(10_u128.pow(18)));

    Ok(())
}