This chapter begins with a discussion on the common uses of the Proxy Pattern. It then explains the implementation of a pre‐fetching proxy. The scenario is, of course, the JavaScript Conference's website. A proxy presents a challenge because the internals are exactly what you do want to test. In the present example, the external behavior of the proxy is to give you profiles as you ask for them. The internal behavior is whether, in addition, the proxy has prepared others for likely delivery. A proxy should be tested by observing its interaction with the real subject, rather than exposing the internals of the proxy. To facilitate testing and dependency injection, pass the proxy's real subject as a parameter to the function that creates the proxy. The test‐driven development should be started with a do‐nothing proxy.