Writing aimock Test Fixtures

What aimock Is

aimock is a zero-dependency mock infrastructure for AI apps. Fixture-driven. Multi-provider (OpenAI, Anthropic, Gemini, AWS Bedrock, Azure OpenAI, Vertex AI, Ollama, Cohere). Multimedia endpoints (image generation, text-to-speech, audio transcription, video generation). MCP, A2A, AG-UI, and vector DB mocking. Runs a real HTTP server on a real port — works across processes, unlike MSW-style interceptors. WebSocket support for OpenAI Responses/Realtime and Gemini Live APIs. Record-and-replay for all endpoints including multimedia. Chaos testing and Prometheus metrics.

Core Mental Model

• Fixtures = match criteria + response
• First-match-wins — order matters
• All providers share one fixture pool (provider adapters normalize to ChatCompletionRequest)
• Fixtures are live — mutations after start() take effect immediately
• Sequential responses are supported via sequenceIndex (match count tracked per fixture)

Match Field Reference