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

via NuGet (package manager for Microsoft development platform)

Install-Package SinonJS

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 for documentation on usage.

If you have questions that are not covered by the documentation, please post them to the Sinon.JS mailinglist or drop by #sinon.js on irc.freenode.net:6667

Important: AMD needs pre-built version

Sinon.JS as source doesn't work with AMD loaders (when they're asynchronous, like loading via script tags in the browser). For that you will have to use a pre-built version. You can either build it yourself or get a numbered version from http://sinonjs.org.

This might or might not change in future versions, depending of outcome of investigations. Please don't report this as a bug, just use pre-built versions.

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?

See CONTRIBUTING.md for details on how you can contribute to Sinon.JS