Sinon JS

• https://semaphoreci.com/community/tutorials/best-practices-for-spies-stubs-and-mocks-in-sinon-js
• https://codeutopia.net/blog/2016/05/23/sinon-js-quick-tip-how-to-stubmock-complex-objects-such-as-dom-objects/

Check if a method is called

const spy = sinon.spy(object, 'method')
...
spy.restore() // remove spy
expect(spy.callCount).to.be.eql(n) // check if the method is call n times