---
title: "Add tests and checks before the app grows · Agent Wranglers"
url: https://agentwranglers.se/playbook/ai-assisted-development/apps-built-with-ai-builders/checks-before-growth
updated: 2026-10-20
licence: "All rights reserved"
---

# Add tests and checks before the app grows

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Recommended
- Chapter: [Apps built with AI builders](https://agentwranglers.se/playbook/ai-assisted-development/apps-built-with-ai-builders)
- Rule: Once users depend on the app, add tests and a check command before adding more features.
- How: Builder output often has no tests, so every new prompt can break old features without anyone noticing. Start with tests for sign-in, payments and the main user path. Then follow [setting up the project](https://agentwranglers.se/playbook/ai-assisted-development/setting-up-the-project).
- Check: The repository has a check command that runs tests for sign-in, payment and the main path, and it passes.

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers ai development playbook: https://agentwranglers.se/playbook/ai-assisted-development/apps-built-with-ai-builders/checks-before-growth`.

- Previous: [Own the code in your own repository](https://agentwranglers.se/playbook/ai-assisted-development/apps-built-with-ai-builders/own-the-code)
- Next: [Know when to move off the builder](https://agentwranglers.se/playbook/ai-assisted-development/apps-built-with-ai-builders/know-when-to-move)
- [Apps built with AI builders](https://agentwranglers.se/playbook/ai-assisted-development/apps-built-with-ai-builders)