## Contracts

Smart contracts that implement the 0x protocol. Addresses of the deployed contracts can be found in the 0x [wiki](https://0xproject.com/wiki#Deployed-Addresses) or the [CHANGELOG](./CHANGELOG.json) of this package.

## Usage

Contracts that make up and interact with version 2.0.0 of the protocol can be found in the [contracts](./contracts) directory. The contents of this directory are broken down into the following subdirectories:

*   [protocol](./contracts/protocol)
    *   This directory contains the contracts that make up version 2.0.0. A full specification can be found [here](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/v2-specification.md).
*   [extensions](./contracts/extensions)
    *   This directory contains contracts that interact with the 2.0.0 contracts and will be used in production, such as the [Forwarder](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/forwarder-specification.md) contract.
*   [examples](./contracts/examples)
    *   This directory contains example implementations of contracts that interact with the protocol but are _not_ intended for use in production. Examples include [filter](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/v2-specification.md#filter-contracts) contracts, a [Wallet](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/v2-specification.md#wallet) contract, and a [Validator](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/v2-specification.md#validator) contract, among others.
*   [tokens](./contracts/tokens)
    *   This directory contains implementations of different tokens and token standards, including [wETH](https://weth.io/), ZRX, [ERC20](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md), and [ERC721](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md).
*   [multisig](./contracts/multisig)
    *   This directory contains the [Gnosis MultiSigWallet](https://github.com/gnosis/MultiSigWallet) and a custom extension that adds a timelock to transactions within the MultiSigWallet.
*   [utils](./contracts/utils)
    *   This directory contains libraries and utils that are shared across all of the other directories.
*   [test](./contracts/test)
    *   This directory contains mocks and other contracts that are used solely for testing contracts within the other directories.

## Bug bounty

A bug bounty for the 2.0.0 contracts is ongoing! Instructions can be found [here](https://0xproject.com/wiki#Bug-Bounty).

## Contributing

We strongly recommend that the community help us make improvements and determine the future direction of the protocol. To report bugs within this package, please create an issue in this repository.

For proposals regarding the 0x protocol's smart contract architecture, message format, or additional functionality, go to the [0x Improvement Proposals (ZEIPs)](https://github.com/0xProject/ZEIPs) repository and follow the contribution guidelines provided therein.

Please read our [contribution guidelines](../../CONTRIBUTING.md) before getting started.

### Install Dependencies

If you don't have yarn workspaces enabled (Yarn < v1.0) - enable them:

```bash
yarn config set workspaces-experimental true
```

Then install dependencies

```bash
yarn install
```

### Build

To build this package and all other monorepo packages that it depends on, run the following from the monorepo root directory:

```bash
PKG=contracts yarn build
```

Or continuously rebuild on change:

```bash
PKG=contracts yarn watch
```

### Clean

```bash
yarn clean
```

### Lint

```bash
yarn lint
```

### Run Tests

```bash
yarn test
```

#### Testing options

###### Revert stack traces

If you want to see helpful stack traces (incl. line number, code snippet) for smart contract reverts, run the tests with:

```
yarn test:trace
```

**Note:** This currently slows down the test runs and is therefore not enabled by default.

###### Backing Ethereum node

By default, our tests run against an in-process [Ganache](https://github.com/trufflesuite/ganache-core) instance. In order to run the tests against [Geth](https://github.com/ethereum/go-ethereum), first follow the instructions in the README for the devnet package to start the devnet Geth node. Then run:

```bash
TEST_PROVIDER=geth yarn test
```

###### Code coverage

In order to see the Solidity code coverage output generated by `@0x/sol-cov`, run:

```
yarn test:coverage
```

###### Gas profiler

In order to profile the gas costs for a specific smart contract call/transaction, you can run the tests in `profiler` mode.

**Note:** Traces emitted by ganache have incorrect gas costs so we recommend using Geth for profiling.

```
TEST_PROVIDER=geth yarn test:profiler
```

You'll see a warning that you need to explicitly enable and disable the profiler before and after the block of code you want to profile.

```typescript
import { profiler } from './utils/profiler';
profiler.start();
// Some call to a smart contract
profiler.stop();
```

Without explicitly starting and stopping the profiler, the profiler output will be too busy, and therefore unusable.