In the previous post I introduced the concept of using Rewire with Jasmine-Node to simplify Node.js unit testing. Rewire added a __set__ and a __get__ function to the module which let us grab a function in the module, and test it directly. We could test the function's output by controlling the objects that the function worked with, and checking them upon function completion. We didn't need to manipulate any internals of the function so our testing is still honoring the "Black Box" concept of unit testing. The idea is that the unit test only cares about what the testee can take in, return, and manipulate outside itself. How that operation is performed is not important to the unit test.
There was one test we didn't look at which I want to discuss now.