DEFI Crash Course: DEX Exercise 1 - Chocolate Factory

Intro

This exercise will get you working with the Uniswap V2 Factory and Router Smart Contracts.

You will deploy a new token, create a pair for it with ETH, and create helper functions to add / remove liquidity and swap tokens.

Eventually, you'll have to write some tests to make sure everything works.

Note: This exercise is executed on an Ethereum mainnet Fork block number 15969633.Everything is already configured in the hardhat.config.js file

Ethereum MAINNET Addresses

• Uniswap V2 Router: 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D
• WETH Token: 0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2

Accounts

• 0 - Deployer
• 1 - User

Tasks

Task 1 - Contract Creation

Complete all the open TODOs in Chocolate.sol.

• Upon token construction, create a pair for your token with WETH using the Uniswap V2 Factory.
• Complete the addChocolateLiquidity admin-only function, and add the liquidity using the Uniswap V2 router. The function will send the LP tokens to the smart contract owner.
• Complete the removeChocolateLiquidity admin-only function, and remove the liquidity using the Uniswap V2 router. The function will send the tokens to the smart contract owner.
• Complete the swapChocolate user's function, and swap the tokens using the Uniswap V2 router. The function will send the tokens to the user who swapped the tokens.

Task 2 - Tests

Complete all the open TODOs in test/dex-1/tests.js

Deployment

• Deploy the chocolate smart contract
• Get the newly deployed pair address, and print it using console.log
• Load and store the pair smart contract

Deployer Adds Liquidity

• Using your contract, add liquidity for Choclate & ETH
• Print the amount of LP tokens the deployer owns

User Swapping

• Form the user account, swap 10 ETH to chocolates
• Make sure the swap succeded by comparing the before and after balances
• Form the user account, swap 100 chocolates to ETH
• Make sure the swap succeded by comparing the before and after balances

Deployer Removes Liquidity

• Using your contract, remove 50% of the deployer's liquidity
• Make sure deployer owns 50% of the LP tokens (leftovers)
• Make sure deployer got chocolates and WETH back (greater amount than before)