Build Awesome Command-Line Applications in Ruby 2

Testing User Behavior with Acceptance Tests

Unlike web applications, command-line apps have simple user interfaces, and their output is less complex. This makes the job of simulating input and testing output relatively simple. The problems come in when we consider what our apps do. db_backup.rb takes a long time to do its work and requires access to a database. todo makes irreversible changes to its task list. We need a way to run our apps that mimics as closely as possible the “real-world” scenarios they were written to solve but in a repeatable and predictable way that doesn’t cause permanent changes to our environment.

Rather than solve this problem at the same time we learn about the mechanics of testing, let’s take things one step at ...