Test data written after the code gets shaped by the code, and then it stops being evidence.
If I write the fixtures after the module, I write the fixtures the module handles. The gaps I would have found are exactly the gaps I no longer think to look for.
---
title: "Fixtures before the module"
description: "Test data written after the code gets shaped by the code, and then it stops being evidence."
url: "https://lateano.com/writing/fixtures-before-the-module"
author: "Colin Lateano"
published: "2026-07-25"
tags:
- title: "How I work"
url: "https://lateano.com/tags/how-i-work"
---
# Fixtures before the module
Test data written after the code gets shaped by the code, and then it stops being evidence.
If I write the fixtures after the module, I write the fixtures the module handles. The gaps I would have found are exactly the gaps I no longer think to look for.