What Is Sinon Testing

Sinon JS is a popular JavaScript library that lets you replace complicated parts of your code that are hard to test for “placeholders,” so you can keep your unit tests fast and deterministic, as they should be.

Why do we need Sinon?

Put simply, Sinon allows you to replace the difficult parts of your tests with something that makes testing simple. When testing a piece of code, you don’t want to have it affected by anything outside the test. If something external affects a test, the test becomes much more complex and could fail randomly.

What is Sinon sandbox?

JS. Sandboxes simplify working with fakes that need to be restored and/or verified. If you’re using fake timers, fake XHR, or you are stubbing/spying on globally accessible properties you should use a sandbox to ease cleanup.