ai-testing

Deterministic testing around non-deterministic LLM components in TypeScript with vitest - fake and scripted model clients, recording and replaying provider responses, fixtures, contract tests for tool schemas and structured output, testing orchestration and agent loops with fake models, property and invariant checks, streaming and error-path tests, snapshot cautions, flaky test handling, and keeping cost-aware live tests separate from the default suite. Load when writing tests for chat, agent, tool or RAG code, mocking provider calls, or fixing flaky AI tests.