I never thought fixtures were dead. I thought they were expensive — and for a decade, they were. Keeping a fixture set coherent across a growing schema, polymorphic associations, and years of feature work was real, ongoing work that FactoryBot let us defer. That tradeoff earned its place.

Then I started migrating SafariPortal – a production Rails 8 / Hotwire app with years of RSpec specs back to Minitest and fixtures, with Claude Code as my pair. And something I didn't expect happened: the maintenance cost that justified factories for a decade just isn't there anymore. The agent keeps the fixture graph coherent. The suite got faster. And the real surprise – Claude Code itself got noticeably smarter about my application code once the test data became declarative YAML.