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ethereum-waffle
Advanced tools
Library for writing and testing smart contracts.
Sweeter and simpler than truffle.
Works with ethers-js. Tastes best with ES6.
To start using with npm, type:
npm i ethereum-waffle
or with Yarn:
yarn add ethereum-waffle
Below is example contract written in Solidity. Place it in contracts
directory of your project:
pragma solidity ^0.4.24;
import "../BasicToken.sol";
contract BasicTokenMock is BasicToken {
constructor(address initialAccount, uint256 initialBalance) public {
balances[initialAccount] = initialBalance;
totalSupply_ = initialBalance;
}
}
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';
chai.use(solidity);
const {expect} = chai;
describe('Example', () => {
let provider;
let token;
let wallet;
let walletTo;
beforeEach(async () => {
provider = createMockProvider();
[wallet, walletTo] = await getWallets(provider);
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(wallet.address)).to.eq(993);
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 from empty account', async () => {
const tokenFromOtherWallet = contractWithWallet(token, walletTo);
await expect(tokenFromOtherWallet.transfer(wallet.address, 1))
.to.be.revertedWith('Not enough balance on sender account');
});
});
To compile contracts simply type:
npx waffle
To compile using custom configuration file:
npx waffle config.json
Example configuration file looks like this:
{
"sourcesPath": "./custom_contracts",
"targetPath": "./custom_build",
"npmPath": "./custom_node_modules"
}
To run test type in the console:
mocha
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
Import solidity files from solidity files form npm modules that you added to your project, e.g:
import "openzeppelin-solidity/contracts/math/SafeMath.sol";
Create a mock provider (no need to run any tests!) and test your contracts against it, e.g.:
provider = createMockProvider();
Get wallets you can use to sign transactions:
[wallet, walletTo] = await getWallets(provider);
Deploy a contract:
token = await deployContract(wallet, BasicTokenMock, [wallet.address, 1000]);
Link a library:
myLibrary = await deployContract(wallet, MyLibrary, []);
link(LibraryConsumer, 'MyLibrary', myLibrary.address);
libraryConsumer = await deployContract(wallet, LibraryConsumer, []);
A set of sweet chai matchers, makes your test easy to write and read. Below couple of examples.
expect(await token.balanceOf(wallet.address)).to.eq(993);
Available matchers for BigNumbers are: equal
, eq
, above
, below
, least
, most
.
await expect(token.transfer(walletTo.address, 7))
.to.emit(token, 'Transfer')
.withArgs(wallet.address, walletTo.address, 7);
await expect(token.transfer(walletTo.address, 1007)).to.be.reverted;
await expect(token.transfer(walletTo.address, 1007)).to.be.revertedWith('Insufficient funds');
expect('0x28FAA621c3348823D6c6548981a19716bcDc740e').to.be.properAddress;
expect('0x706618637b8ca922f6290ce1ecd4c31247e9ab75cf0530a0ac95c0332173d7c5').to.be.properPrivateKey;
expect('0x70').to.be.properHex(2);
await expect(() => myContract.transferWei(receiverWallet.address, 2)).to.changeBalance(receiverWallet, 2);
Note: transaction call should be passed to the expect as a callback (we need to check the balance before the call). The matcher can accept numbers, strings and BigNumbers as a balance change, while the address should be specified as a wallet.
changeBalance calls should not be chained. If you need to chain it, you probably want to use changeBalances matcher.
await expect(() => myContract.transferWei(receiverWallet.address, 2)).to.changeBalances([senderWallet, receiverWallet], [-2, 2]);
FAQs
Sweeter, faster and simpler than truffle.
The npm package ethereum-waffle receives a total of 31,725 weekly downloads. As such, ethereum-waffle popularity was classified as popular.
We found that ethereum-waffle demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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