chai.md

   1 ---
   2 title: Chai.js
   3 category: JavaScript libraries
   4 layout: 2017/sheet
   5 weight: -3
   6 updated: 2018-06-25
   7 version: chai v4.x
   8 description: |
   9   expect(x).to.be.equal(y) 〉 assert.equal(x, y) 〉 .to.be.true 〉 jQuery, assertions, TDD and BDD, and other Chai examples.
  10 ---
  11
  12 ### Assert
  13
  14 ```js
  15 const { assert } = require('chai')
  16 ```
  17 {: .-setup}
  18
  19 ```js
  20 assert(val)
  21 assert.fail(actual, expected)
  22 assert.ok(val)                        // is truthy
  23 assert.equal(actual, expected)        // compare with ==
  24 assert.strictEqual(actual, expected)  // compare with ===
  25 assert.deepEqual(actual, expected)    // deep equal check
  26 ```
  27
  28 ```js
  29 assert.isTrue(val)
  30 assert.isFalse(val)
  31 ```
  32
  33 ```js
  34 assert.isNull(val)
  35 assert.isNotNull(val)
  36 assert.isUndefined(val)
  37 assert.isDefined(val)
  38 assert.isFunction(val)
  39 assert.isObject(val)
  40 assert.isArray(val)
  41 assert.isString(val)
  42 assert.isNumber(val)
  43 assert.isBoolean(val)
  44 ```
  45
  46 ```js
  47 assert.typeOf(/tea/, 'regexp') // Object.prototype.toString()
  48 assert.instanceOf(chai, Tea)
  49 assert.include([ a,b,c ], a)
  50 assert.match(val, /regexp/)
  51 assert.property(obj, 'tea') // 'tea' in object
  52 assert.deepProperty(obj, 'tea.green')
  53 assert.propertyVal(person, 'name', 'John')
  54 assert.deepPropertyVal(post, 'author.name', 'John')
  55 ```
  56
  57 ```js
  58 assert.lengthOf(object, 3)
  59 assert.throws(function() { ... })
  60 assert.throws(function() { ... }, /reference error/)
  61 assert.doesNotThrow
  62 ```
  63
  64 ```js
  65 assert.operator(1, '<', 2)
  66 assert.closeTo(actual, expected)
  67 ```
  68
  69 See: [Assert API](http://chaijs.com/api/assert/) _(chaijs.com)_
  70
  71 ### BDD syntax
  72
  73 ```js
  74 const { expect } = require('chai')
  75 ```
  76 {: .-setup}
  77
  78 ```js
  79 expect(object)
  80   .to.equal(expected)
  81   .to.eql(expected)        // deep equality
  82   .to.deep.equal(expected) // same as .eql
  83   .to.be.a('string')
  84   .to.include(val)
  85 ```
  86
  87 ```js
  88   .be.ok(val)
  89   .be.true
  90   .be.false
  91   .to.exist
  92 ```
  93
  94 ```js
  95   .to.be.null
  96   .to.be.undefined
  97   .to.be.empty
  98   .to.be.arguments
  99   .to.be.function
 100   .to.be.instanceOf
 101 ```
 102
 103 ```js
 104   .to.be.gt(5)  // aka: .above .greaterThan
 105   .to.be.gte(5) // aka: .at.least
 106   .to.be.lt(5)  // aka: .below
 107 ```
 108
 109 ```js
 110   .to.respondTo('bar')
 111   .to.satisfy((n) => n > 0)
 112 ```
 113
 114 ```js
 115   .to.have.members([2, 3, 4])
 116   .to.have.keys(['foo'])
 117   .to.have.key('foo')
 118   .to.have.lengthOf(3)
 119 ```
 120
 121 ```js
 122 expect(() => { ··· })
 123   .to.throw(/not a function/)
 124 ```
 125
 126 See: [BDD](http://chaijs.com/api/bdd/) _(chaijs.com)_
 127
 128 ### Should: chains
 129
 130     .to .be .been .is .that .and .have .with .at .of .same
 131
 132 These don't do anything and can be chained.
 133
 134 ### Should not
 135
 136 ```js
 137 expect(object).not.equal('x')
 138 ```
 139
 140 ## Chai with jQuery
 141
 142 ### Using chai-jquery
 143
 144 ```js
 145 global.jQuery = ···
 146 chai.use(require('chai-jquery'))
 147 ```
 148 {: .-setup}
 149
 150 ```js
 151 expect($body)
 152   .have.attr('foo')
 153   .have.prop('disabled')
 154   .have.css('background')
 155   .have.css('background-color', '#ffffff')
 156   .have.data('foo')
 157 ```
 158
 159 ```js
 160   .have.class('active')
 161   .have.id('id')
 162 ```
 163
 164 ```js
 165   .have.html('<em>hi</em>')
 166   .have.text('hello')
 167   .have.value('2013')
 168 ```
 169
 170 ### Continued
 171
 172 ```js
 173 expect($body)
 174 ```
 175
 176 ```js
 177   .be.visible
 178   .be.hidden
 179 ```
 180
 181 ```js
 182   .be.checked
 183   .be.selected
 184 ```
 185
 186 ```js
 187   .be.enabled
 188   .be.disabled
 189 ```
 190
 191 ```js
 192   .be.empty
 193   .to.exist
 194   .to.contain('text')
 195   .to.have('.selector')
 196 ```