SinonJS provides stand alone test spies, stubs and mocks. This is the mechanism we’ll be using to create our spies, stubs and mocks.
Spies: Creates fake functions which we can use to track executions. This means we can tell/ find out whether the function has been executed/ how many times its been called etc. We can also use spies on existing functions and get the same capability, to track those functions executions. We’ll see this in action a bit later.
Stubs: Enables us to replace functions. This gives us more control. We can return whatever we want or have our functions work in a way that suites us to be able to test multiple scenarios.
Mocks: They are fake methods, that have pre-programmed behavior and pre-programmed expectations.
Sinonjs provides all these mechanisms, makes us write extensive unit tests.
