FauxJS

A very basic function mocking and call assertion library.

Installation

Via NPM:

npm install fauxjs

It should work out of the box with RequireJS and AMD.

var faux = require('fauxjs')

If neither RequireJS or AMD are found, the faux function is added to the window object.

Usage

Faux creates a mock method, optionally wrapped around a callback.

// Arrange:
var broker = new Broker()
broker.sell = faux()

// Act:
broker.enact(portfolio, instructions)

// Assert:
broker.sell.wasCalled()

If the broker.sell method wasn't called, an exception is thrown.

A callback can be passed to wasCalled, allowing conditions to be applied to the check. Each time the mocked method is called the arguments are recorded, and the callback is called against each of these sets of arguments:

broker.sell.wasCalled(function(x) {
	return x[0] == 'BHP' && x[1] == 4000
})

There is a corresponding wasNotCalled method that just reverses the logic.

Mocking Angular services

Angular's $http service is usually used by chaining .then() calls to the promise. For example:

$http
	.post('/some/api', {
		id: 123
	})
	.then(function(x) { 
		$state.go('nextPage')
	})

Faux can be used to create a simple mock $http service to support this:

// Arrange:
var $http = {
	post: faux(function() {
		return {
			then: faux(function(success, error) {
				return success()
			})
		}
	})
}
var $state = {
	go: faux()
}
var controller = new MyController($http)

// Act:
controller.action()

// Assert:
$http.post.wasCalled(function(x) {
	return x[0] == '/some/api' && x[1].id == 123
})
$state.go.wasCalled(function(x) {
	return x[0] == 'nextPage'
})

TODO

• Pass a call count to wasCalled/wasNotCalled: fn.wasCalled(2) (fn was called 2 times), fn.wasCalled(x => x[0] == 123, 2) (fn was called matching the conditions 2 times)