Lesson 993 of 1596
Deterministic Replay With Tool Mocks for Agent Tests
Build a mock harness that lets you replay agent runs deterministically in CI.
Creators · Agentic AI · ~7 min read
The premise
Real tool calls in tests are flaky and expensive — mock harnesses keep agent tests fast and stable.
What AI does well here
- Record real tool responses for use as mocks.
- Replay against a fixed seed for stable runs.
- Allow override of specific calls for what-if analysis.
What AI cannot do
- Catch issues caused by real tool changes after recording.
- Eliminate model nondeterminism without seed control.
Key terms in this lesson
Practice this safely
Use a small project example from your own work. The useful move is to compare the AI's draft against your goal, sources, and constraints before you trust it.
- 1Ask AI to explain mock tools in plain language, then underline anything that sounds uncertain or too broad.
- 2Give it one detail from "Deterministic Replay With Tool Mocks for Agent Tests" and ask for two possible next steps plus one reason each step might be wrong.
- 3Check deterministic test against a trusted source, teacher, adult, expert, or original document before you use it.
End-of-lesson quiz
Check what stuck
10 questions · Score saves to your progress.
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