install-nix-action/node_modules/jest-circus/README.md
Domen Kožar 70742d22d9
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2019-11-19 17:50:30 +01:00

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<h1 align="center">
<img src="https://jestjs.io/img/jest.png" height="150" width="150"/>
<img src="https://jestjs.io/img/circus.png" height="150" width="150"/>
<p align="center">jest-circus</p>
<p align="center">The next-gen test runner for Jest</p>
</h1>
## Overview
Circus is a flux-based test runner for Jest that is fast, easy to maintain, and simple to extend.
Circus allows you to bind to events via an optional event handler on any [custom environment](https://jestjs.io/docs/en/configuration#testenvironment-string). See the [type definitions](https://github.com/facebook/jest/blob/master/packages/jest-circus/src/types.ts) for more information on the events and state data currently available.
```js
import {NodeEnvironment} from 'jest-environment-node';
import {Event, State} from 'jest-circus';
class MyCustomEnvironment extends NodeEnvironment {
//...
handleTestEvent(event: Event, state: State) {
if (event.name === 'test_start') {
// ...
}
}
}
```
Mutating event or state data is currently unsupported and may cause unexpected behavior or break in a future release without warning. New events, event data, and/or state data will not be considered a breaking change and may be added in any minor release.
## Installation
Install `jest-circus` using yarn:
```bash
yarn add --dev jest-circus
```
Or via npm:
```bash
npm install --save-dev jest-circus
```
## Configure
Configure Jest to use `jest-circus` via the [`testRunner`](https://jestjs.io/docs/en/configuration#testrunner-string) option:
```json
{
"testRunner": "jest-circus/runner"
}
```
Or via CLI:
```bash
jest --testRunner='jest-circus/runner'
```