sinon

What is sinon?

Sinon is a testing utility that provides functions for spies, stubs, and mocks, which are essential for behavior-driven development and testing in JavaScript. It works with any unit testing framework and is widely used for its versatile API and comprehensive feature set.

What are sinon's main functionalities?

Spies

Spies are functions that record their usage, such as how many times they were called, with what arguments, and what was returned. They can be used to wrap existing functions to add this tracking ability.

const sinon = require('sinon');
const myFunction = sinon.spy();
myFunction('Hello', 'World');
console.log(myFunction.calledOnce); // true

Stubs

Stubs are like spies, but they can replace the target function's behavior, either by returning a specific value or by throwing an exception. They are useful for controlling a function's behavior in a test.

const sinon = require('sinon');
const myObj = { myMethod: () => 'original' };
const stub = sinon.stub(myObj, 'myMethod').returns('stubbed');
console.log(myObj.myMethod()); // 'stubbed'

Mocks

Mocks are fake methods (like stubs) with pre-programmed behavior and expectations. They are used to assert that certain methods are called in certain ways.

const sinon = require('sinon');
const myObj = { myMethod: () => 'original' };
const mock = sinon.mock(myObj);
mock.expects('myMethod').once().returns('mocked');
console.log(myObj.myMethod()); // 'mocked'
mock.verify();

Other packages similar to sinon

jest

Jest is a complete testing framework that comes with spies, mocks, and stubs built-in. It is often compared to Sinon for its mocking capabilities, but Jest provides a more integrated experience with a test runner and assertion library included.

testdouble

Testdouble.js (npm package 'testdouble') is a minimalistic testing library that provides a similar API to Sinon for creating test doubles like stubs, mocks, and spies. It focuses on providing a more user-friendly experience with better error messages and simpler APIs.

chai-spies

Chai-spies is a plugin for the Chai assertion library that adds spy capabilities. While it doesn't offer as comprehensive a set of features as Sinon, it integrates well with Chai for developers who prefer that assertion style.

README

Sinon.JS

Standalone and test framework agnostic JavaScript test spies, stubs and mocks.

Installation

via npm (node package manager)

$ npm install sinon

or install via git by cloning the repository and including sinon.js in your project, as you would any other third party library.

Don't forget to include the parts of Sinon.JS that you want to use as well (i.e. spy.js).

Usage

See the sinon project homepage

Goals

• No global pollution
• Easy to use
• Require minimal “integration”
• Easy to embed seamlessly with any testing framework
• Easily fake any interface
• Ship with ready-to-use fakes for XMLHttpRequest, timers and more

Contribute?

Pick an issue to fix, or pitch new features. To avoid wasting your time, please ask for feedback on feature suggestions either with an issue or on the mailing list.

Run the tests

The Sinon.JS developer environment requires Node/NPM. Please make sure you have Node installed, and install Sinon's dependencies:

$ npm install

On Node

$ npm test

In the browser

Open test/sinon.html in a browser. To test against a built distribution, first make sure you have a build (requires Ruby and Juicer):

$ ./build

Then open test/sinon-dist.html in a browser.

If the build script is unable to find Juicer, try

$ ruby -rubygems build

Some tests needs working XHR to pass. To run the tests over an HTTP server, run

$ node_modules/http-server/bin/http-server

Then open localhost:8080/test/sinon.html in a browser.

On Rhino

The Rhino tests are currently out of commission (pending update after switch to Buster.JS for tests).

Changelog

1.7.1

• Fake XMLHttpRequest updated to call onerror and onsuccess callbacks, fixing jQuery 2.0 problems (Roman Potashow)
• Implement XMLHttpRequest progress event api (Marten Lienen)
• Added sinon.restore() (Jonny Reeves)
• Fix bug where throwing a string was handled incorrectly by Sinon (Brandon Heyer)
• Web workers support (Victor Costan)