Reactively Writing Unit Tests for Domain Objects

The simplest, fastest, and easiest way to test anything is at the unit level. A unit is most commonly expressed in Java as a single class. In essence, a unit test involves verifying a single class acts properly by removing any external collaborators.

Why is this the simplest way to test?

This is because there’s little machinery needed to put this together. In fact, we can do this without any machinery. However, it’s handy to use something like JUnit 5 to at least gather the results. In ...