AIMock — Mock LLM, MCP, A2A, Vector APIs

Practical Notes

• Mocks many surfaces from one port (LLM APIs, MCP, A2A, vector/search/rerank, etc.)
• Supports 12 LLM providers (per project docs) and streaming behaviors for realistic tests
• GitHub stars/forks (verified): see Source & Thanks

AIMock pays for itself the first time you avoid a flaky test or a surprise token bill.

Use it in three steps:

1. Start llmock (fixtures-first) or the full suite via --config.
2. Point your SDK to the mock by setting OPENAI_BASE_URL (and a dummy key if the SDK requires it).
3. Record real traces once (optional), then replay deterministically in CI forever.

Two good guardrails:

• Keep fixtures in version control and review them like code.
• Add a CI check that fails if your tests accidentally talk to real endpoints (base URL not patched).

FAQ

Q: What does it mock? A: LLM APIs plus agent protocols like MCP/A2A and common infra like vector DBs, search, and rerank.

Q: Can it record real responses? A: Yes — it supports record & replay so you can capture and replay fixtures deterministically.

Q: How do I adopt it safely? A: Patch base URLs via env vars in tests and add a CI guard to prevent real endpoint calls.