chai-css

Extends Chai with assertions about css.

Getting Started

$ npm i --save-dev chai-css

const Chai = require('chai')
const chaiCss = require('chai-css')
const expect = Chai.expect

Chai.use(chaiCss)

expect('.foo {width:10rem;}').to.have.rule('.foo')
expect('.foo {width:10rem;}').to.not.have.decl('height')
expect('@media (max-width: 10px) { .foo { width:10px; } }').to.have.atRule('media', '(max-width: 10px)')

expect('test/fixtures/style.css').to.have.rule('.a')
  .and.decl({
    width: '10px',
    webkitTransform: 'scale(1)'
  })

Usage

chai-css is dependent on PostCSS. It extends rule, atRule and decl for Chai, which are common in PostCSS. With the three methods, we can easily make assertion for CSS.

If you never meet PostCSS before, you should know:

• rule is a selector in CSS, like "#wrap .item"
• atRule is a CSS statement beginning with an at sign " @ ", like "@media (max-width: 10px)"
• decl is CSS declaration, like "width"

First you should use the plugin in Chai.

import Chai, { expect } from 'chai'
import chaiCss from 'chai-css'

Chai.use(chaiCss)

rule

expect('#main .foo {width:10px;}').to.have.rule('#main .foo')
expect('#main .foo {width:10px;}').to.not.have.rule('#main')

atRule

expect('@media (max-width: 10px) {.foo{width:10px;}}').to.have.atRule('media')
expect('@media (max-width: 10px) {.foo{width:10px;}}').to.have.atRule('media', '(max-width: 10px)')
expect('@media (max-width: 10px) {.foo{width:10px;}}').to.not.have.atRule('media', '(max-height: 5px)')
expect('@charset "UTF-8";').to.have.atRule('charset', '"UTF8"')

decl

expect('.foo { width: 10px; }').to.have.decl('width')
expect('.foo { width: 10px; }').to.not.have.decl('height')
expect('.foo { font-size: 16px; }').to.have.decl('font-size', '16px')
expect('.foo { width: 10px; width: 1rem; }').to.have.decl('width', '10px').and.decl('width', '1rem')
expect('.foo { width: 10px; font-size: 16px; }').to.have.decl({
  width: '10px',
  fontSize: '16px'
})

expect('.foo {width:10rem;width:10px;} .bar {width:0;color:#fff;}').to.have.rule('.foo')
  .and.decl('width', '10px')
  .and.decl('width', '10rem')
  .and.not.have.decl('width', '0')
  .and.not.have.decl('color')

expect('@media (max-width: 10px) { .foo { width:10px; } }')
  .to.have.atRule('media', '(max-width: 10px)')
  .and.rule('.foo')
  .and.decl('width', '10px')

You can also provide a css file directly.

expect('test/fixtures/style.css').to.have.rule('.a')
  .and.decl({
    width: '10px',
    webkitTransform: 'scale(1)'
  })

To make assertions of Stylus or SASS directly, you can provide a synchronous function and it will be executed before each assertion.

As Stylus:

import Chai, { expect } from 'chai'
import chaiCss from 'chai-css'
import stylus from 'stylus'

const preprocessor = raw => stylus.render(raw)
Chai.use(chaiCss(preprocessor))

expect(`
  $white = #fff
  $black = #000

  .foo
    color $white
    background $black
`)
  .to.have.rule('.foo')
  .and.decl('color', '#fff')
  .and.decl('background', '#000')

// OR

expect('text/fixtures/test.styl').to.have.rule('.foo')

Test

$ npm i && npm test

License

MIT