Mistral builds an agent on Vibe that writes Rails tests automatically

Rails testing on autopilot: Building an agent that writes what developers won't

Mistral built an agent on its open-source coding assistant Vibe that writes Rails RSpec tests on its own. It reads source code, generates or improves tests, checks them against style rules and coverage targets, and runs unattended in CI/CD.

Why it matters: Mistral published its full method for building an auto-RSpec-test agent on Vibe, including transferable details on context engineering, skill files and custom tools.