196 lines
3.1 KiB
Markdown
196 lines
3.1 KiB
Markdown
---
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title: Chai.js
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category: JavaScript libraries
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weight: -3
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updated: 2018-06-25
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version: chai v4.x
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description: |
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expect(x).to.be.equal(y) 〉 assert.equal(x, y) 〉 .to.be.true 〉 jQuery, assertions, TDD and BDD, and other Chai examples.
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---
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### Assert
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```js
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const { assert } = require('chai')
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```
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{: .-setup}
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```js
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assert(val)
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assert.fail(actual, expected)
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assert.ok(val) // is truthy
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assert.equal(actual, expected) // compare with ==
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assert.strictEqual(actual, expected) // compare with ===
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assert.deepEqual(actual, expected) // deep equal check
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```
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```js
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assert.isTrue(val)
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assert.isFalse(val)
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```
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```js
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assert.isNull(val)
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assert.isNotNull(val)
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assert.isUndefined(val)
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assert.isDefined(val)
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assert.isFunction(val)
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assert.isObject(val)
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assert.isArray(val)
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assert.isString(val)
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assert.isNumber(val)
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assert.isBoolean(val)
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```
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```js
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assert.typeOf(/tea/, 'regexp') // Object.prototype.toString()
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assert.instanceOf(chai, Tea)
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assert.include([ a,b,c ], a)
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assert.match(val, /regexp/)
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assert.property(obj, 'tea') // 'tea' in object
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assert.deepProperty(obj, 'tea.green')
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assert.propertyVal(person, 'name', 'John')
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assert.deepPropertyVal(post, 'author.name', 'John')
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```
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```js
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assert.lengthOf(object, 3)
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assert.throws(function() { ... })
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assert.throws(function() { ... }, /reference error/)
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assert.doesNotThrow
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```
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```js
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assert.operator(1, '<', 2)
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assert.closeTo(actual, expected)
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```
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See: [Assert API](http://chaijs.com/api/assert/) _(chaijs.com)_
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### BDD syntax
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```js
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const { expect } = require('chai')
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```
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{: .-setup}
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```js
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expect(object)
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.to.equal(expected)
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.to.eql(expected) // deep equality
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.to.deep.equal(expected) // same as .eql
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.to.be.a('string')
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.to.include(val)
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```
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```js
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.be.ok(val)
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.be.true
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.be.false
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.to.exist
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```
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```js
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.to.be.null
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.to.be.undefined
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.to.be.empty
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.to.be.arguments
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.to.be.function
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.to.be.instanceOf
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```
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```js
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.to.be.gt(5) // aka: .above .greaterThan
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.to.be.gte(5) // aka: .at.least
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.to.be.lt(5) // aka: .below
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```
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```js
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.to.respondTo('bar')
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.to.satisfy((n) => n > 0)
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```
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```js
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.to.have.members([2, 3, 4])
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.to.have.keys(['foo'])
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.to.have.key('foo')
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.to.have.lengthOf(3)
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```
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```js
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expect(() => { ··· })
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.to.throw(/not a function/)
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```
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See: [BDD](http://chaijs.com/api/bdd/) _(chaijs.com)_
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### Should: chains
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.to .be .been .is .that .and .have .with .at .of .same
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These don't do anything and can be chained.
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### Should not
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```js
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expect(object).not.equal('x')
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```
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## Chai with jQuery
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### Using chai-jquery
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```js
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global.jQuery = ···
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chai.use(require('chai-jquery'))
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```
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{: .-setup}
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```js
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expect($body)
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.have.attr('foo')
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.have.prop('disabled')
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.have.css('background')
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.have.css('background-color', '#ffffff')
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.have.data('foo')
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```
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```js
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.have.class('active')
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.have.id('id')
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```
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```js
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.have.html('<em>hi</em>')
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.have.text('hello')
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.have.value('2013')
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```
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### Continued
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```js
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expect($body)
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```
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```js
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.be.visible
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.be.hidden
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```
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```js
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.be.checked
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.be.selected
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```
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```js
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.be.enabled
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.be.disabled
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```
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```js
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.be.empty
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.to.exist
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.to.contain('text')
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.to.have('.selector')
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```
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