# Santiago shows how to test an agent with a digital twin using Claude Code

> Original title: I built an agent and tested it without writing a single line of code.

- Source: Santiago
- Published: 2026-11-11T16:57:52.000Z
- Bad Influence: https://badinfluence.news/items/xbeun5czynv3uw4wqfdsp52hr
- Original: https://x.com/svpino/status/2120561659605668198

## Summary

Santiago says he built an agent and tested it without writing any code, using Claude Code to create a digital twin of the agent. He says the setup mocks every tool the agent touches and simulates its functions without affecting production, and that the test surfaces problems and suggests fixes.

## Post

I built an agent and tested it without writing a single line of code.

Here is how to create a digital twin of your agent, mock every tool it touches, and simulate every function it runs without affecting production.

I'm using Claude Code here.

Probably the closest thing to magic you'll see this month.

This will test and discover problems with your agent that you didn't even know were possible.

It will then tell you how to fix everything it finds.

[Video](https://badinfluence.news/api/img-proxy?u=https%3A%2F%2Fpbs.twimg.com%2Famplify_video_thumb%2F2120561547663794176%2Fimg%2Fve6kHLHMr1jINhsE.jpg&mode=thumb&exp=1794700800&sig=e4b13f55f2339ff2)