Use Waffle

There are multiple tools you can use to develop and compile Solidity contracts, we'd present two here as options

• online web app Remix

• Solidity development and testing framework Waffle

Compile Solidity Contract using Waffle Comment

Note: you can skip this section if you compiled the smart contract with Remix.

This guide walks through the process of deploying a Solidity-based smart contract to Acala using Waffle. Waffle is one of the most commonly used smart contract development frameworks for Ethereum.

1. Check Prerequisites

First, we need to install Node.js (we use v15.x in this example) and the npm package manager. For installation follow guides in the official documentation for your operating system: install NodeJS

We can verify that everything installed correctly by querying the version for each package:

node -v

npm -v

Install yarn package manager:

npm install --global yarn

Check if it's installed correctly:

yarn -v

2. Using Waffle With Our Examples

We've made it easy by collecting all required dependencies in the AcalaNetwork/evm-examples repo.

Simply clone the repository and install the dependencies.

git clone https://github.com/AcalaNetwork/evm-examples
cd evm-examples/erc20

yarn install

3. Using Waffle from Scratch (optional)

Alternatively, you can install each library separately as the following:

Create a project folder smart-contract-waffle

mkdir smart-contract-waffle
cd smart-contract-waffle

Initiate package manager

yarn init -y

Install all following dependencies

yarn add --dev @openzeppelin/contracts@3.3.0 ethereum-waffle@3.2.1

Note: it's recommended to install dependencies with exact versions as specified to avoid breaking changes.

Then create a waffle settings file

touch waffle.json

Paste the following in the waffle.json file

 {
    "compilerType": "solcjs",
    "compilerVersion": "0.6.2",
    "sourceDirectory": "./contracts",
    "outputDirectory": "./build"
  }

This sets up the solidity compiler with version 0.6.2, compiles contracts from the ./contracts folder, and saves the bytecode output and ABI files to ./build folder.

Now create the ./contracts folder, and add the BasicToken.sol contract.

mkdir contracts
touch contracts/BasicToken.sol

Paste the following content into the BasicToken.sol file and save.

pragma solidity ^0.6.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

// Example class - a mock class using delivering from ERC20
contract BasicToken is ERC20 {
    constructor(uint256 initialBalance) public ERC20("Basic", "BSC") {
        _mint(msg.sender, initialBalance);
    }
}

4. Compile the Smart Contract

Now compile the contract into ABI and bytecode. Run the following in the terminal

yarn waffle

5. Get the ABI file

Waffle will then generate the output file ./build/BasicToken.json into the ./build folder.

Note: this file should be the same as the one created with Remix.

Waffle also provides a full suite of testing utilities, check out their documentation and code samples here.