path: root/packages/contracts/README.md

## Contracts

Smart contracts that implement the 0x protocol.

## Usage

*   [Docs](https://0xproject.com/docs/contracts)
*   [Overview of 0x protocol architecture](https://0xproject.com/wiki#Architecture)
*   [0x smart contract interactions](https://0xproject.com/wiki#Contract-Interactions)
*   [Deployed smart contract addresses](https://0xproject.com/wiki#Deployed-Addresses)
*   [0x protocol message format](https://0xproject.com/wiki#Message-Format)

## 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 `@0xproject/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.