Getting Started


To start using with npm, type:

npm i ethereum-waffle

or with Yarn:

yarn add ethereum-waffle

Adding a contract

Below is example contract written in Solidity. Place it in contracts directory of your project:

pragma solidity ^0.5.1;

import "openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";

// Example class - a mock class using delivering from ERC20
contract BasicTokenMock is ERC20 {
  constructor(address initialAccount, uint256 initialBalance) public {
    super._mint(initialAccount, initialBalance);

Writing first tests

Belows is example test written for the contract above written with Waffle. Place it in test directory of your project:

import chai from 'chai';
import {createMockProvider, deployContract, getWallets, solidity} from 'ethereum-waffle';
import BasicTokenMock from './build/BasicTokenMock';
import MyLibrary from './build/MyLibrary';
import LibraryConsumer from './build/LibraryConsumer';

const {expect} = chai;

describe('INTEGRATION: Example', () => {
  let provider = createMockProvider();
  let [wallet, walletTo] = getWallets(provider);
  let token;

  beforeEach(async () => {
    token = await deployContract(wallet, BasicTokenMock, [wallet.address, 1000]);

  it('Assigns initial balance', async () => {
    expect(await token.balanceOf(wallet.address)).to.eq(1000);

  it('Transfer adds amount to destination account', async () => {
    await token.transfer(walletTo.address, 7);
    expect(await token.balanceOf(walletTo.address)).to.eq(7);

  it('Transfer emits event', async () => {
    await expect(token.transfer(walletTo.address, 7))
      .to.emit(token, 'Transfer')
      .withArgs(wallet.address, walletTo.address, 7);

  it('Can not transfer above the amount', async () => {
    await expect(token.transfer(walletTo.address, 1007));

  it('Can not transfer from empty account', async () => {
    const tokenFromOtherWallet = token.connect(walletTo);
    await expect(tokenFromOtherWallet.transfer(wallet.address, 1));



To compile contracts simply type:

npx waffle

To compile using custom configuration file:

npx waffle config.json

Example configuration file looks like this:

  "sourcesPath": "./contracts",
  "targetPath": "./build",
  "npmPath": "./node_modules"

Running tests

To run test type in the console:


Adding a task

For convince, you can add a task to your package.json. In the sections scripts, add following line:

"test": "waffle && test"

Now you can build and test your contracts with one command:

npm test