https://github.com/mattphillips/jest-chain

Chain Jest matchers together to create one powerful assertion 🃏⛓
https://github.com/mattphillips/jest-chain

assertions chain chainable dry expect expressive fail-fast jest matchers

Last synced: 10 days ago
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Chain Jest matchers together to create one powerful assertion 🃏⛓

• Host: GitHub
• URL: https://github.com/mattphillips/jest-chain
• Owner: mattphillips
• License: mit
• Created: 2018-05-02T22:21:29.000Z (over 6 years ago)
• Default Branch: main
• Last Pushed: 2023-01-09T08:38:47.000Z (almost 2 years ago)
• Last Synced: 2024-10-15T18:43:49.873Z (24 days ago)
• Topics: assertions, chain, chainable, dry, expect, expressive, fail-fast, jest, matchers
• Language: JavaScript
• Homepage: https://www.npmjs.com/package/jest-chain
• Size: 432 KB
• Stars: 275
• Watchers: 4
• Forks: 16
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • Contributing: CONTRIBUTING.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

Awesome Lists containing this project

• awesome-jest - jest-chain

README

        


  
jest-chain


🃏⛓

Chain Jest matchers together to create one powerful assertion





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- 🍸 Less code duplication

- 🤗 Chain core and custom matchers together

- 👾 Expressive assertions

- 🚨 Fail fast assertions

## Problem

Often in [Jest](https://facebook.github.io/jest/) when you are writing tests you may want to perform multiple assertions on the

same variable. Currently to achieve this you have to write an individual `expect` for each

assertion.

For example:

```js

it("add 1 and 1", () => {

  const actual = 1 + 1;

  expect(actual).toBe(2);

  expect(actual).toBeGreaterThan(1);

  expect(actual).toBeLessThan(3);

});

```

With `jest-chain` this can instead be written by chaining the matchers together:

```js

it("add 1 and 1", () => {

  expect(1 + 1)

    .toBe(2)

    .toBeGreaterThan(1)

    .toBeLessThan(3);

});

```

## Installation

With npm:

```sh

npm install --save-dev jest-chain

```

With yarn:

```sh

yarn add -D jest-chain

```

## Setup

Add `jest-chain` to your Jest `setupFilesAfterEnv` configuration. [See for help](https://jestjs.io/docs/en/next/configuration#setupfilesafterenv-array)

### Jest >v24

```json

"jest": {

  "setupFilesAfterEnv": ["jest-chain"]

}

```

### Jest