Waffle is a library for writing and testing smart contracts. Sweeter, simpler and faster than Truffle.

1. Sweeter smart contract testing

2. Philosophy
Faster SweeterSimpler
Minimalistic, a couple of helpers,
matchers and tasks rather than a
framework,
few dependencies.
Faster contract compilation.
Faster test execution.
Nice syntax, fast,
easy to extend.

3. Basic features
Create a mock provider
provider = createMockProvider();
[wallet, walletTo] = getWallets(provider);
Get example wallets
token = await deployContract(wallet, BasicTokenMock, [wallet.address, 1000]);
Deploy contract
Linking
myLibrary = await deployContract(wallet, MyLibrary, []);
link(LibraryConsumer, 'path/to/file/MyLibrary.sol/MyLibrary', myLibrary.address);
libraryConsumer = await deployContract(wallet, LibraryConsumer, []);
npm i open-zeppelin
Import contracts from nom library
import "openzeppelin-solidity/contracts/math/SafeMath.sol";

4. Chai matchers
Bignumbers
expect(await token.balanceOf(wallet.address)).to.eq(993);
Emitting events
await expect(token.transfer(walletTo.address, 1007)).to.be.reverted;
Revert
await expect(token.transfer(walletTo.address, 7))
.to.emit(token, 'Transfer')
.withArgs(wallet.address, walletTo.address, 7);

5. Chai matchers
Revert with message
Change balance
await expect(token.transfer(walletTo.address, 1007)).to.be.reverted;
Change balance (multiple accounts)
await expect(() => myContract.transferWei(receiverWallet.address, 2))
.to.changeBalance(receiverWallet, 2);
await expect(token.transfer(walletTo.address, 1007))
.to.be.revertedWith('Insufficient funds');
await expect(() => myContract.transferWei(receiverWallet.address, 2))
.to.changeBalances([senderWallet, receiverWallet], [-2, 2]);

6. Fixtures
import {expect} from 'chai';
import {loadFixture, deployContract} from 'ethereum-waffle';
import BasicTokenMock from './build/BasicTokenMock';
describe('Fixtures', () => {
async function fixture(provider, [wallet, other]) {
const token = await deployContract(wallet, BasicTokenMock, [
wallet.address, 1000
]);
return {token, wallet, other};
}
it('Assigns initial balance', async () => {
const {token, wallet} = await loadFixture(fixture);
expect(await token.balanceOf(wallet.address)).to.eq(1000);
});
it('Transfer adds amount to destination account', async () => {
const {token, other} = await loadFixture(fixture);
await token.transfer(other.address, 7);
expect(await token.balanceOf(other.address)).to.eq(7);
});
});

7. Others
Fast compilation
• Native solc
• Dockerized solc
Configuration
• Monorepo
• Solcjs and version management
• Legacy / Truffle compatibility
• Custom compiler options

8. Roadmap
Faster testing with native geth Debugging Profiling Code coverage

9. Projects that use Waffle
Counterfactual Universal Login SDK
1703
Weekly downloads
Star 110 Watch 3 Fork 12

10. Websites
getwaffle.io github.com/waffle ethereum-waffle.readthedocs.io

11. Contact
Marek Kirejczyk
@ethmarek