I Ran 170 Agent Goals for $0.49. The Field Test Found 10 Issues That Unit Tests Never Would.

7.9 relevance

Field test of 170 agent goals for $0.49 uncovering issues unit tests miss, highly actionable for agent testing and observability.

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Why It Matters

For engineers building agentic systems, this demonstrates that unit tests are insufficient for catching prompt-level and integration bugs, and that a structured field test combined with thorough code review can serve as a reliable regression gate before costly LLM runs.

Key Takeaways

Treat field tests as regression gates, not diagnostics—invest in code review to catch bugs before the LLM runs, so zero field failures become a signal of quality, not a broken harness.

I Ran 170 Agent Goals for $0.49. The Field Test Found 10 Issues That Unit Tests Never Would.

Summary

A field test of the PlannerCritic agent engine across 170 goals at $0.49 found zero issues in v0.2.1, but only because code review caught all 41 bugs before the LLM ran. In v0.1.0, the same test found 10 issues—including harness bugs, prompt gaps, and design flaws—that unit tests missed entirely, such as 57 of 65 assertion files being in the wrong format with no error. The arc shows the field test evolving from a diagnostic tool into an immutable regression gate, where zero failures now signals rigorous pre-release review rather than a broken harness.

Author

Debashish Ghosal