jest-environment-hardhat

jest-environment-hardhat

A jest environment with hardhat built in.

jest-environment-hardhat is a drop-in jest environment for running hardhat inline with your tests. Instead of running a separate hardhat node, this environment runs a node and exposes a global Hardhat interface to interact with it.

Installation

First, install jest-environment-hardhat and its dependencies using yarn.

The environment needs @nomiclabs/hardhat-ethers, ethers, and hardhat installed to run. These are installed as peer dependencies to ensure that you retain control over versioning.

yarn add -D @nomiclabs/hardhat-ethers ethers hardhat
yarn add -D jest-environment-hardhat

Then, use the runner either using a doc-comment, or using jest configuration. See the jest documentation for more.

jest-environment-hardhat extends a node environment by default. A jsdom environment is also available, using jest-environment-hardhat/dist/jsdom.

Using a doc-comment

Files starting with a @jest-environment preamble use the specified runner:

/**
 * @jest-environment jest-environment-hardhat
 */

Using jest configuration

You may also configure your test environment through the jest.config.js file, using the testEnvironment property.

  "testEnvironment": "jest-environment-hardhat",

Subclassing your own runner

jest-environment-hardhat exports a node and jsdom environment. If you'd like to extend your own environment, you can use the setup function exported by jest-environment-hardhat/setup. See src/node.ts for an example.

Documentation

Using the environment will expose hardhat on the global scope, which you can use to interact with the hardhat network in your tests.

For documentation on the hardhat global, see the type definitions.

For examples of how to interact with the hardhat network, see the tests.

Typescript

If you are using Typescript, you can import types by adding import jest-environment-hardat to your test file, or by adding jest-environment-hardhat types to your tsconfig.

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