📜 SimpleSwap

📌 Essential Information

Solidity Pragma: 0.8.27

Network: Sepolia

Contract:

• TokenA 0xb5BAd729930d785F35F2CCD8E1C9284E7058c322
• TokenB 0xE13096D1C36F134C63Dd451DA43afFc0fb839eF3
• SimpleSwap 0x8A899B1F91a787fC4B30b664477b3b5D1A849166
• Verificador_Profesor Hash: 0x74d7c20e447802fa71397af1d13ecb62412f5a0e61615b73fa314cb6c060736f
• Debugger Tenderly

Owner: 0x39581f1c36CfeBfB36934E583fb3e3CE92Ba6c58

Version: 1.10

License: MIT

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General Description

SimpleSwap is a foundational Decentralized Exchange (DEX) smart contract. It draws inspiration from the core Automated Market Maker (AMM) principles of Uniswap V2, providing a simplified yet functional implementation for understanding liquidity provision and token swapping on the blockchain.

This contract allows users to:

• Establish and manage liquidity pools for a specific pair of ERC-20 tokens.
• Execute direct token swaps between the two assets within the pool.
• Add and remove liquidity enabling them to earn a share of the trading fees generated by swaps.

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Setup and Usage

1. Requirements

• Development Environment: Remix IDE (Injected Provider - Metamask for a testnet like Sepolia)

• Dependencies: OpenZeppelin Contracts.

  npm install @openzeppelin/contracts

2. Deployment (Step-by-step in Remix)

2.1. Open Remix IDE: Go to Remix IDE.

2.2. Select Environment: In the Deploy & Run Transactions tab (the Ethereum logo icon), choose JavaScript VM for local testing. If using a public testnet like Sepolia, select Injected Provider - Metamask and connect your wallet.

2.3. Create Token Files:

• Create MockTokenA.sol
• Create MockTokenB.sol

2.4. Deploy ERC-20 Tokens:

• Compile MockTokenA.sol.
• In the Deploy & Run Transactions tab, select MockTokenA from the dropdown and click Deploy. Copy the deployed address (e.g., 0xc475...).
• Repeat for MockTokenB.sol, copying its deployed address (e.g., 0x9dAf...).

2.5. Deploy SimpleSwap:

• Compile SimpleSwap.sol.
• In the Deploy & Run Transactions tab, select SimpleSwap from the dropdown.
• In the Deploy section, locate the constructor fields: _tokenA and _tokenB.
• Paste the deployed address of your MockTokenA into _tokenA.
• Paste the deployed address of your MockTokenB into _tokenB.
• Click Deploy. Copy the deployed SimpleSwap address (e.g., 0xa42b...).

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3. Step-by-Step Testing in Remix

Use the deployed contract addresses from your Remix session:

• Token A: 0x7c87b552996ebd58dc76f5809fb4476cf189ac00
• Token B: 0x5544A7c23557Cc9fa410Ac1Aaa43713daA477D49
• SimpleSwap: 0x216051a12dd8365dE1F4AdD61e952134562662d7
• Account: 0x39581f1c36CfeBfB36934E583fb3e3CE92Ba6c58

3.1. Approve Tokens for SimpleSwap

Before SimpleSwap can move your tokens, you need to grant it permission using the approve function on each token.

• Select your TokenA contract in the Deployed Contracts section.
• Expand the approve function.
  • Spender:Enter 0x216051a12dd8365dE1F4AdD61e952134562662d7 (SimpleSwap address).
  • amount: Enter 1000000000000000000000 (e.g., 1000 TKA).
  • Click transact.
• Repeat the process for your TokenB contract.

3.2. Add Liquidity

Now, let's add some liquidity to the SimpleSwap pool.

• Select your SimpleSwap contract in the Deployed Contracts section.
• Expand the addLiquidity function.
  • _tokenA_param
  • _tokenB_param:
  • amountADesired: 100000000000000000000 (100 TKA)
  • amountBDesired: 200000000000000000000 (200 TKB)
  • amountAMin: 90000000000000000000 (90 TKA)
  • amountBMin: 180000000000000000000 (180 TKB)
  • to: 0x39581f1c36CfeBfB36934E583fb3e3CE92Ba6c58 (account address)
  • deadline: Math.floor(Date.now() / 1000) + 600 (in Consola)
  • Click transact.
• Expected Output: You should see a successful transaction and in the decoded output:

{
    "0": "uint256: amountA 100000000000000000000",   // 100 TKA
    "1": "uint256: amountB 200000000000000000000",   // 200 TKB
    "2": "uint256: liquidity 141421356237309503880"  // Approx. 141.42 LP tokens
}

3.3. Swap Exact Tokens For Tokens

Let's exchange some tokens. Ensure you have approved enough TokenA (or TokenB if swapping the other way)

• Select your SimpleSwap contract in the Deployed Contracts section.
• Expand the swapExactTokensForTokens function.
  • amountIn: 10000000000000000000 (10 TKA)
  • amountOutMin: 18000000000000000000 (18 TKB - adjust this value if you get a "Slippage" or "InsufficientOutputAmount" error)

path: Crucial for Remix and Sepolia! Enter this as a JSON array string:

["0x7c87b552996ebd58dc76f5809fb4476cf189ac00", "0x5544A7c23557Cc9fa410Ac1Aaa43713daA477D49"]

❗ Make sure to format the path correctly, or the function will fail.

• Continue
  • to: 0x39581f1c36CfeBfB36934E583fb3e3CE92Ba6c58 (or your account address)
  • deadline: Math.floor(Date.now() / 1000) + 600 (in Consola)
  • Click transact
• Expected Output: If successful, you will see a Swap event and the decoded output will be an array like:

[
  "10000000000000000000", // amountIn (10 TKA)
  "amountOut"                     // (The actual amount of TKB received)
]

3.4. Remove Liquidity

Finally, remove some of the liquidity you provided.

• Select your SimpleSwap contract.
• Expand the removeLiquidity function.
  • _tokenA_param
  • _tokenB_param:
  • liquidity: The amount of LP tokens you received in Step 2 (e.g., 141421356237309503880).
  • amountAMin: 0 (or a small minimum)
  • amountBMin: 0 (or a small minimum)
  • to: 0x39581f1c36CfeBfB36934E583fb3e3CE92Ba6c58 (account address)
  • deadline: Math.floor(Date.now() / 1000) + 600 (in Consola)
  • Click transact.
• Expected Output: You should see a Burn event and the decoded output will show the amounts of TokenA and TokenB returned to your address.

📇 Project Information

Student: Elisa Araya
Course: ETH Kipu - Ethereum Developer Pack
Submission: Final Assignment - Module 3