puppet.challenge.js

const exchangeJson = require("../../build-uniswap-v1/UniswapV1Exchange.json");
const factoryJson = require("../../build-uniswap-v1/UniswapV1Factory.json");

const { ethers } = require('hardhat');
const { expect } = require('chai');
const { setBalance } = require("@nomicfoundation/hardhat-network-helpers");

// Calculates how much ETH (in wei) Uniswap will pay for the given amount of tokens
function calculateTokenToEthInputPrice(tokensSold, tokensInReserve, etherInReserve) {
    return (tokensSold * 997n * etherInReserve) / (tokensInReserve * 1000n + tokensSold * 997n);
}

describe('[Challenge] Puppet', function () {
    let deployer, player;
    let token, exchangeTemplate, uniswapFactory, uniswapExchange, lendingPool;

    const UNISWAP_INITIAL_TOKEN_RESERVE = 10n * 10n ** 18n;
    const UNISWAP_INITIAL_ETH_RESERVE = 10n * 10n ** 18n;

    const PLAYER_INITIAL_TOKEN_BALANCE = 1000n * 10n ** 18n;
    const PLAYER_INITIAL_ETH_BALANCE = 25n * 10n ** 18n;

    const POOL_INITIAL_TOKEN_BALANCE = 100000n * 10n ** 18n;

    before(async function () {
        /** SETUP SCENARIO - NO NEED TO CHANGE ANYTHING HERE */
        [deployer, player] = await ethers.getSigners();

        const UniswapExchangeFactory = new ethers.ContractFactory(exchangeJson.abi, exchangeJson.evm.bytecode, deployer);
        const UniswapFactoryFactory = new ethers.ContractFactory(factoryJson.abi, factoryJson.evm.bytecode, deployer);

        setBalance(player.address, PLAYER_INITIAL_ETH_BALANCE);
        expect(await ethers.provider.getBalance(player.address)).to.equal(PLAYER_INITIAL_ETH_BALANCE);

        // Deploy token to be traded in Uniswap
        token = await (await ethers.getContractFactory('DamnValuableToken', deployer)).deploy();

        // Deploy a exchange that will be used as the factory template
        exchangeTemplate = await UniswapExchangeFactory.deploy();

        // Deploy factory, initializing it with the address of the template exchange
        uniswapFactory = await UniswapFactoryFactory.deploy();
        await uniswapFactory.initializeFactory(exchangeTemplate.address);

        // Create a new exchange for the token, and retrieve the deployed exchange's address
        let tx = await uniswapFactory.createExchange(token.address, { gasLimit: 1e6 });
        const { events } = await tx.wait();
        uniswapExchange = await UniswapExchangeFactory.attach(events[0].args.exchange);

        // Deploy the lending pool
        lendingPool = await (await ethers.getContractFactory('PuppetPool', deployer)).deploy(
            token.address,
            uniswapExchange.address
        );

        // Add initial token and ETH liquidity to the pool
        await token.approve(
            uniswapExchange.address,
            UNISWAP_INITIAL_TOKEN_RESERVE
        );
        await uniswapExchange.addLiquidity(
            0,                                                          // min_liquidity
            UNISWAP_INITIAL_TOKEN_RESERVE,
            (await ethers.provider.getBlock('latest')).timestamp * 2,   // deadline
            { value: UNISWAP_INITIAL_ETH_RESERVE, gasLimit: 1e6 }
        );

        // Ensure Uniswap exchange is working as expected
        expect(
            await uniswapExchange.getTokenToEthInputPrice(
                10n ** 18n,
                { gasLimit: 1e6 }
            )
        ).to.be.eq(
            calculateTokenToEthInputPrice(
                10n ** 18n,
                UNISWAP_INITIAL_TOKEN_RESERVE,
                UNISWAP_INITIAL_ETH_RESERVE
            )
        );

        // Setup initial token balances of pool and player accounts
        await token.transfer(player.address, PLAYER_INITIAL_TOKEN_BALANCE);
        await token.transfer(lendingPool.address, POOL_INITIAL_TOKEN_BALANCE);

        // Ensure correct setup of pool. For example, to borrow 1 need to deposit 2
        expect(
            await lendingPool.calculateDepositRequired(10n ** 18n)
        ).to.be.eq(2n * 10n ** 18n);

        expect(
            await lendingPool.calculateDepositRequired(POOL_INITIAL_TOKEN_BALANCE)
        ).to.be.eq(POOL_INITIAL_TOKEN_BALANCE * 2n);
    });

    it('Execution', async function () {
        /** CODE YOUR SOLUTION HERE */
    });

    after(async function () {
        /** SUCCESS CONDITIONS - NO NEED TO CHANGE ANYTHING HERE */
        // Player executed a single transaction
        expect(await ethers.provider.getTransactionCount(player.address)).to.eq(1);

        // Player has taken all tokens from the pool       
        expect(
            await token.balanceOf(lendingPool.address)
        ).to.be.eq(0, 'Pool still has tokens');

        expect(
            await token.balanceOf(player.address)
        ).to.be.gte(POOL_INITIAL_TOKEN_BALANCE, 'Not enough token balance in player');
    });
});