Sinon.JS is a popular JavaScript testing utility that provides standalone test spies, stubs, and mocks. Use it to verify function calls, replace real implementations with controlled substitutes, and simulate different behaviors. Sinon helps you write cleaner, more readable, and easier-to-maintain tests by allowing you to isolate units of code and control their dependencies during testing. It seamlessly integrates with any JavaScript testing framework.
Sinon's release frequency has varied significantly since December 2010. There have been periods of intense activity (e.g., 2017-2018), followed by quieter spells. 2023 saw a resurgence in releases, particularly in October. 2024 had several months with releases, but 2025 has been sparse.
Sinon's npm package downloads show a generally upward trend from February 2024 to July 2025, peaking at over 39 million downloads. There was a significant jump in March 2024. August 2025 downloads are incomplete and significantly lower, reflecting the partial month. Overall, the package demonstrates consistent and high usage.
