The Test That Lied to Me: A practical guide to writing unit tests that actually mean something

The Test That Lied to Me A practical guide to writing unit tests that actually mean something A quick note before we start: there is a lot of enthusiasm lately about AI generating unit tests automatically. I have tried it. The results were technically valid, consistently green, and almost completely useless — which, if you think about it, is a perfect description of most of the unit tests in the industry. So here we are. Maybe this helps the AI write better tests. Maybe it just helps the engineers. Either way, I felt the need to write it down. This guide is not about coverage percentages or which framework to use. It is about the decisions that determine whether your test suite is an asset or an alibi. The examples in this guide use Java with JUnit 5 and Mockito. The principles apply everywhere. Part 1: The Name Is the Specification Before a test does anything, it declares what it expects. That declaration lives in the name. A bad test name is a lost opportunity. Not just for documenta