freeCodeCamp/guide/english/miscellaneous/testing-with-chaijs/index.md

title
Testing with Chaijs

Chai is a testing library for Node.js.

Installation

You can install Chai in your project through npm.

npm install chai

Pro-tip

Add Chai in devDependencies of package.json, using * as version tag. In this way, you always have the most recent version.

"devDependencies": {
  "chai": "*"
}

How to use

Assert

You can use assert to check if your tests are performing well.

var assert = require('chai').assert, foo = 'bar', beverages = { tea: [ 'chai', 'matcha', 'oolong' ] };

assert.typeOf(foo, 'string'); // without optional message
assert.typeOf(foo, 'string', 'foo is a string'); // with optional message
assert.equal(foo, 'bar', 'foo equal `bar`');
assert.lengthOf(foo, 3, 'foo`s value has a length of 3');
assert.lengthOf(beverages.tea, 3, 'beverages has 3 types of tea');

More info:

• help chai assert
• help chai expectations