Designing Elixir Systems With OTP

Test Your Code

One of the benefits of structuring your project into core and boundary layers is that our coding organization will simplify testing. With a basic API layer that does most of the business logic, you’ll be able to write tests to thoroughly exercise your business code should you choose to do so. You’ll be able to represent your testing concepts in any way you choose, and we’ll discuss a few strategies as the book evolves.

We will focus on unit testing here with ExUnit, but the same principles apply to property-based testing, a philosophy that allows you to specify properties about your code so that the computer can generate many different tests. For now, let’s write a simple test for our counter. We’ll start with the business logic. ...