# 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](https://github.com/EthWorks/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](https://nodejs.org/en/download/package-manager/)

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](https://github.com/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](https://github.com/EthWorks/Waffle).


---

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