When we write unit tests it's good practice to "mock" out extraneous bits to the code being tested. It's almost like the scientific method in that testing, in the unit testing paradigm, means exercising each small portion of your code in isolation if only to eliminate unwanted variables. While there are other testing paradigms, unit testing has its value. A big question for Node.js web application programmers is - how do you mock out HTTP requests for unit testing? In other words, how do you test the route handler method in isolation from the Node.js HTTPServer object, or Express, or whatever app framework used in your application?