You write your code. You build your software component. Or the AI agent does it for you, it does not matter.

Then you ask an AI agent to build on it: an application, another layer, maybe several. You have it test what it built. You do not assess the original work directly. You assess how good the software built on top of it is.

It is a form of integration testing. The difference is that the software on top is entirely ephemeral. You throw it away when you are done.

A library with a clean API, stable invariants, and useful errors lets the agent produce something that works quickly. A library with hidden state, surprising defaults, or incomplete docs produces a pile of patches and failures. The failures are evidence about your code, not about the agent.

Ephemeral testing - Daniel Lemire's blog
https://lemire.me/blog/2026/10/05/ephemeral-testing/