Mark Baker has returned with a new part of his series looking at the use of anonymous classes and closures as an alternative to the typical test mocking functionality. In this latest part (part four) he talks more about the "SpyMaster" class created in the previous article and how it can be refactored to provide the spies with a "mission".

In a prior article in this series, I described the use of a SpyMaster Class to create proxy spies as anonymous classes, that allow external visibility (and potentially update) of protected and private properties within an object. The same basic principle of a spy can also be used to create a proxy that gives us access to execute the private and protected methods of an object.

[...] Unlike the original SpyMaster that I wrote about last July, we’re going to take a slightly different approach here, providing our spies with a “mission”.

He first shares the code for the old class and covers why it was useful. He then moves on to the refactor, showing how it defines the "mission" (what to mock) and an "invoker" that helps with the actual execution. He gives an example of this new class in use, performing an "infiltration" on a sample object and calling previously protected methods directly.