Spies
Spies
Introduction
What is a test spy?
A test spy is a function that records arguments, return value, the value of this and exception thrown (if any) for all its calls. There are two types of spies: Some are anonymous functions, while others wrap methods that already exist in the system under test.
Creating a spy as an anonymous function
When the behavior of the spied-on function is not under test, you can use an anonymous function spy. The spy won’t do anything except record information about its calls. A common use case for this type of spy is testing how a function handles a callback, as in the following simplified example:
"test should call subscribers on publish": function () {
var callback = sinon.spy();
PubSub.subscribe("message", callback);
PubSub.publishSync("messa
