Woken up by PagerDuty at 2 AM. The user group was on fire — our AI customer service agent suddenly lost its memory. One message confirmed the user's phone number, the next asked "How may I address you?" Checking the logs revealed that the Redis connection pool threw a ConnectionError during a network hiccup. Our supposedly bulletproof mock tests had never simulated that exception. The code simply skipped memory persistence, and all context was lost. Even scarier: the regression suite was green.
This is a textbook disaster of having mocks without real-middleware tests. We spent two weeks rebuilding the automated verification of the agent’s memory module with pytest + a real Redis instance. The result: online memory-related bugs went from a 30% leakage rate to zero. Here’s the full blueprint, code, and the sharp edges we found along the way.
1. Why mocks can't catch the real risks of an agent memory module
An agent’s memory isn’t simple key-value storage. It handles three things:
Short-term memory: the last N turns of dialogue, stored in a Redis List or ZSet with TTL-based eviction.
