Skip Real Inference in Agent Tests: Mock LLM Responses for Determinism

zwerp · x · 2026-10-07

A developer questions running real LLM inference when testing an agent harness, arguing it adds non-determinism to something that could be tested deterministically—better to mock/simulate LLM responses covering all edge cases. Others note the pain: a single test suite run costing $10.

Related event: Sentry CEO: AI Agent Test Suite Costs $10 Per Run, Sparking Mock-vs-Real-Model Debate(8 posts)→

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