Sinon.JS Test Spies, Stubs, and Mocks

Sinon.js is a widely used, standalone, and test framework-agnostic JavaScript library providing test spies, stubs, and mocks for robust unit testing. The current stable version is 21.1.2. It maintains a consistent release cadence, frequently publishing updates and bug fixes across major versions. Key differentiators include its non-global pollution approach, ease of integration with any testing framework (like Mocha, Jest, or QUnit), and built-in fakes for browser APIs such as timers (setTimeout, setInterval) and XMLHttpRequest. It is designed to be easy to use and requires minimal setup, allowing developers to isolate and test specific units of code effectively by controlling their dependencies and behavior.