Designing Elixir Systems With OTP

Chapter 5 Test Your Core

If you’re like us, you’ve been continuously asking a nagging question as we wrestled the data design and functional core to the ground. Where are the tests?

Here’s a confession. We don’t write code the way it’s presented in this book. In real life, we make more mistakes, switch between data, functions, and tests often. We have debates, spike on feature branches, and we almost always create a test baseline as we go.

That coding style is a great way to work, but a lousy way to write a book like this, and with good reason. A book about layers can’t jerk its readers breathlessly from layer to layer and still hope to teach the core concepts of each one. That’s why we are going to present the tests, fully formed, line by ...