Custom Assertions For Chai

For our integration testing, we have made our own Chai's custom assertions. This is where we define, collect, and present them in a plugin form.

https://www.npmjs.com/package/mobify-chai-assertions

How To Use the Plugin

To use the plugin, simply call Chai's use() function:

var chai = require('node_modules/chai/chai');
var customAssertions = require('node_modules/mobify-chai-assertions/assertions');
chai.use(customAssertions);

New Assertion Methods

The plugin extends Chai by adding the following methods. Feel free to use either the assert or expect styles. They work with any of the chains listed in the Chai API documentation.

(Note: since Chai's API supports only the expect style, we implemented these methods for the expect style first and then the assert style as a wrapper)

Elements

All of these assertions can take an optional msg parameter to output a custom error message on test failure.

[ ] syntax denotes an optional parameter.

element([msg]) / elements([msg])

// Asserts that it is a Zepto/jQuery element.
expect($paymentOptions).to.be.an.element;

// Takes an optional error message that is displayed on failure.
// Default error message is "Must be a Zepto/jQuery object"
expect($paymentOptions).to.be.elements('failure: it is not a Zepto/jQuery object');

//Can be chained with .present and .count (see below)

present([num], [msg])

// Asserts that the length is at least (>=) than num.
// Default is 1. 
// Can be used with all types of expressions.
expect($paymentOptions).to.be.present;

var items = [1, 2, 3];
expect(items).to.be.present;
expect(items).to.be.present(3);
expect(items).to.be.present(4, 'my custom failure message');

// Can be used in a chain:
// Zepto/jQuery object has length at least 1
expect($paymentOptions).to.have.elements.present;

// Can be negated
// Length is 0
expect($paymentOptions).to.have.elements.not.present;

count(num, [msg])

// Asserts that it has a specified length
var items = [1, 2, 3];
expect(items).to.have.count(3);
expect(items).to.have.count(5, 'my custom failure message');

// Asserts that a jQuery/Zepto object has a specified length
var $images = $('img');
expect($images).to.have.elements.count(24);

Deprecated elementsPresent, elementsNotPresent use elements.present and elements.not.present instead:

// Asserts that there exists such element on page
assert.elementsPresent($emailForm)
expect($emailForm).to.have.elementsPresent()

// Asserts that there are 4 or more such elements
assert.elementsPresent($links, 3)
expect($links).to.have.elementsPresent(3)

// The negation
assert.elementsNotPresent($emailForm)
expect($emailForm).to.not.have.elementsPresent()

Deprecated elementsEqual, elementsNotEqual use elements.count instead:

// Asserts that there are exactly 3 of such elements
assert.elementsEqual($images, 3)
expect($images).to.have.elementsEqual(3)

// The negation
assert.elementsNotEqual($images, 3)
expect($images).to.not.have.elementsEqual(3)

Properties

Works with javascript objects.

properties

// Asserts that this object has the keys 'apple' and 'google'
assert.properties(apps, 'apple', 'google')
expect(apps).to.have.properties('apple', 'google')

Items

Works with a collection of things.

items([msg])

// Asserts that this collection (e.g. an array) has at least 1 item in it
expect(lists).to.have.items;
expect(lists).to.have.items('my custom failure message');

Deprecated hasItems use have.items instead:

// Asserts that this collection (e.g. an array) has at least 1 item in it
assert.hasItems(lists)
expect(lists).to.not.be.empty