Sinon.JS is a Standalone test spies, stubs and mocks for JavaScript. No dependencies, works with any unit testing framework. A test spy is a function that records arguments, return value, the value of this and exception thrown (if any) for all its calls.

Test spies are useful to test both callbacks and how certain functions/methods are used throughout the system under test. Use a stub when you want to control a method’s behavior from a test to force the code down a specific path. Mocks are fake methods (like spies) with pre-programmed behavior (like stubs) as well as pre-programmed expectations.

Requirements: -
Demo: http://sinonjs.org/
License: BSD License