@iwehrman Looking into usage of `MockFileSystem.when`, I don't think that's what we want to use here. 

The intent of my addition is to test the jQuery event handler args, it doesn't appear that `MockFileSystem.when` was meant for testing jQuery events at all. 

The use of a spy here in this case is not to mock a method on a class but rather just function as a simple event handler function in order to inspect the invocation and the arguments passed.