Testing LLM Memory Store State Consistency with Pytest

Short summary

A practical guide to testing LLM memory store consistency with Pytest after discovering intermittent amnesia bugs where Redis acknowledged writes but vector stores remained empty. The author models the memory store as a Protocol interface, uses testcontainers-python for isolated backends, and follows a concurrent-writes + multiple-reads + eventual-assertions pattern. The approach caught state inconsistencies that manual curl-based testing and post-mortem reconciliation scripts could never reproduce.

• •LLM memory stores span Redis, vector DBs, and PostgreSQL — async write windows cause intermittent data loss that manual testing can't catch
• •Pytest with testcontainers-python provides isolated, reproducible cross-storage consistency tests in CI
• •MemoryStoreProtocol abstraction lets tests run unchanged when swapping vector DB or caching backends

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