chai

Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework.

For more information or to download plugins, view the [documentation](http://chaijs.com). ## What is Chai? Chai is an _assertion library_, similar to Node's built-in `assert`. It makes testing much easier by giving you lots of assertions you can run against your code. ## Installation ### Node.js `chai` is available on [npm](http://npmjs.org). To install it, type: $ npm install --save-dev chai ### Browsers You can also use it within the browser; install via npm and use the `chai.js` file found within the download. For example: ```html ``` ## Usage Import the library in your code, and then pick one of the styles you'd like to use - either `assert`, `expect` or `should`: ```js import { assert } from 'chai'; // Using Assert style import { expect } from 'chai'; // Using Expect style import { should } from 'chai'; // Using Should style ``` ### Register the chai testing style globally ```js import 'chai/register-assert'; // Using Assert style import 'chai/register-expect'; // Using Expect style import 'chai/register-should'; // Using Should style ``` ### Import assertion styles as local variables ```js import { assert } from 'chai'; // Using Assert style import { expect } from 'chai'; // Using Expect style import { should } from 'chai'; // Using Should style should(); // Modifies `Object.prototype` import { expect, use } from 'chai'; // Creates local variables `expect` and `use`; useful for plugin use ``` ### Usage with Mocha ```bash mocha spec.js --require chai/register-assert.js # Using Assert style mocha spec.js --require chai/register-expect.js # Using Expect style mocha spec.js --require chai/register-should.js # Using Should style ``` [Read more about these styles in our docs](http://chaijs.com/guide/styles/). ## Plugins Chai offers a robust Plugin architecture for extending Chai's assertions and interfaces. - Need a plugin? View the [official plugin list](http://chaijs.com/plugins). - Want to build a plugin? Read the [plugin api documentation](http://chaijs.com/guide/plugins/). - Have a plugin and want it listed? Simply add the following keywords to your package.json: - `chai-plugin` - `browser` if your plugin works in the browser as well as Node.js - `browser-only` if your plugin does not work with Node.js ### Related Projects - [chaijs / chai-docs](https://github.com/chaijs/chai-docs): The chaijs.com website source code. - [chaijs / assertion-error](https://github.com/chaijs/assertion-error): Custom `Error` constructor thrown upon an assertion failing. - [chaijs / deep-eql](https://github.com/chaijs/deep-eql): Improved deep equality testing for Node.js and the browser. - [chaijs / check-error](https://github.com/chaijs/check-error): Error comparison and information related utility for Node.js and the browser. - [chaijs / loupe](https://github.com/chaijs/loupe): Inspect utility for Node.js and browsers. - [chaijs / pathval](https://github.com/chaijs/pathval): Object value retrieval given a string path. ### Contributing Thank you very much for considering to contribute! Please make sure you follow our [Code Of Conduct](https://github.com/chaijs/chai/blob/master/CODE_OF_CONDUCT.md) and we also strongly recommend reading our [Contributing Guide](https://github.com/chaijs/chai/blob/master/CONTRIBUTING.md). Here are a few issues other contributors frequently ran into when opening pull requests: - Please do not commit changes to the `chai.js` build. We do it once per release. - Before pushing your commits, please make sure you [rebase](https://github.com/chaijs/chai/blob/master/CONTRIBUTING.md#pull-requests) them. ### Contributors Please see the full [Contributors Graph](https://github.com/chaijs/chai/graphs/contributors) for our list of contributors. ### Core Contributors Feel free to reach out to any of the core contributors with your questions or concerns. We will do our best to respond in a timely manner. [![Jake Luer](https://avatars3.githubusercontent.com/u/58988?v=3&s=50)](https://github.com/logicalparadox) [![Veselin Todorov](https://avatars3.githubusercontent.com/u/330048?v=3&s=50)](https://github.com/vesln) [![Keith Cirkel](https://avatars3.githubusercontent.com/u/118266?v=3&s=50)](https://github.com/keithamus) [![Lucas Fernandes da Costa](https://avatars3.githubusercontent.com/u/6868147?v=3&s=50)](https://github.com/lucasfcosta) [![Grant Snodgrass](https://avatars3.githubusercontent.com/u/17260989?v=3&s=50)](https://github.com/meeber)

	Stars	Issues	Version	Updated	Created
chai	8,072	95	5.1.1	8 days ago	12 years ago
expect.js	2,101	89	0.3.1	10 years ago	12 years ago
jest	43,641	337	29.7.0	8 months ago	12 years ago
should			13.2.3	6 years ago	13 years ago
sinon			18.0.0	2 days ago	13 years ago
testdouble	1,408	29	3.20.2	2 months ago	9 years ago

chai vs expect.js vs jest vs should vs sinon vs testdouble

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