Before we get started, we need to decide what kind of app we’re going to build: an embedded system, a search engine, a Twitter clone, or what have you. We’ll need to sketch out just enough pieces to decide what technologies we’re going to use. Then, we can set up RSpec in our new project directory. Over the course of the project, you’ll see how outside-in development helps you build a better system.
The Project: An Expense Tracker
We’ll need a project big enough to contain some real-world problems, but small enough to work on over a few chapters. How about a web service for tracking expenses? Customers will use some kind of client software—a command-line app, a GUI, or even a web app—to track and report their daily expenses.