---
title: "Check that outside services still match · Agent Wranglers"
url: https://agentwranglers.se/playbook/testing/integration-and-contract-tests/verify-the-fakes
updated: 2026-10-20
licence: "All rights reserved"
---

# Check that outside services still match your fakes

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

- Level: Optional
- Chapter: [Integration and contract tests](https://agentwranglers.se/playbook/testing/integration-and-contract-tests)
- Rule: Now and then, run a small test against each outside service to prove your fakes still behave like it.
- How: Keep a few tests that call the provider's sandbox, such as a test card charge. Run them on a schedule, not on every change, so their outages never block work. When they fail, update the fake and the code together.
- Check: The scheduled job ran in the last 7 days and passed, or its failure has an open issue.

**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 testing playbook: https://agentwranglers.se/playbook/testing/integration-and-contract-tests/verify-the-fakes`.

- Previous: [Check the contract between services](https://agentwranglers.se/playbook/testing/integration-and-contract-tests/contract-tests)
- [Integration and contract tests](https://agentwranglers.se/playbook/testing/integration-and-contract-tests)