nw-hexagonal-testing

Validate multi-layer agent outputs against an I/O contract by applying a 5-layer validation framework across unit, integration, handoff, and adversarial stages. This process uses per-layer examples and test doubles to ensure deterministic handoffs and structured reviewer sign-off.

Hexagonal testing for agent I/O is a validation method that isolates logic through strict input and output contracts. It applies test doubles policies and layered checks across unit, integration, and adversarial stages to reduce scope creep and ambiguity in multi-layer agent outputs.

Enforce deterministic handoffs in multi-layer agent systems by specifying an I/O contract with explicit validation gates for each layer. Applying a test doubles policy with per-layer examples ensures consistent outputs and reduces ambiguity during handoff stages.

Agent testing fails against adversarial inputs when validation layers lack explicit adversarial checks and robust test doubles. Adding an adversarial validation stage to your I/O contract framework ensures multi-layer agent outputs remain robust against unexpected or malicious inputs.

Yes, this approach supports vertical slice development from UI to infrastructure. The I/O contract framework provides layered validation and test doubles policies that enable end-to-end feature delivery across the entire stack while ensuring deterministic handoffs.