One of the best ways to learn new things is by practically applying the concepts.

I started studying blockchain concepts and technologies used for blockchain development, but I wanted to enhance my understanding and master new skills.

I decided to build a decentralized application.

🚀 What have I learned after finishing the project

I built this decentralized application mainly to learn smart contract development.

But I ended up with a more significant result because even if I was developing just a personal project, I worked on it with the responsibility to learn as many things as possible.

Smart contract development

I understood how Solidity works, how to use existing audited smart contracts and how to protect against several attacks (Authorization through tx.origin, Reentrancy, Assert Violation).

Test-driven development

That was the first time I applied the test-driven methodology. It is hard at the beginning, but it pays off the effort.

After I wrote the test suite, the smart contract development was an easily accomplished task 🍰. I knew exactly what I had to implement in the smart contract.

Liquidity pools

I understood what happens with a pair of tokens inside a liquidity pool when tokens are swapped. More details are available here: Uniswap protocol overview

GitHub Actions

I wanted a way to deploy my application automatically. I discovered that GitHub allows me to host my frontend application free, using GitHub Pages. This is a handy feature from GitHub!

I learnt how to use GitHub Actions and settled the following jobs that are triggered for each commit:

Run tests for the smart contract
Deploy the React application to GitHub Pages

🚀 Description of the project

The application is a decentralized application with similar functionality to a DEX, running on the Ethereum blockchain (Rinkeby testnet), and it provides the following functionalities:

Metamask wallet connection
users can mint tokens to use on the platform
create a pool if it does not exist
add/remove liquidity pool
swap tokens
check token balances

The developed smart contract will keep a 0.01% fee from each swap, and the contract owner can withdraw all the accumulated fees.

🚀 What technologies have I used

Smart contract development

I developed the smart contract using Solidity using the hardhat framework:

Waffle is a hardhat plugin to test the smart contracts
TypeChain is hardhat plugin that generates types. I was excited to find this plugin because I wanted to have the application fully written in typescript.
Uniswap Router is a smart contract that provides functions to add/remove liquidity and swap tokens.
OpenZeppelin is a collection of trusted and audited smart contracts ready to be used. I used it for the Ownable pattern and to deploy the ERC20 tokens used in the application.