What is Policy Testing?

Policies are code. They define logic, have edge cases, and can contain bugs. A policy that accidentally blocks a critical tool call is a production incident. A policy that fails to block a dangerous operation is a security incident. Testing catches both before they reach production.

Policy testing differs from policy dry-run in scope and timing. Dry-run observes policy behaviour against live traffic — it tells you what would happen with real tool calls. Testing validates policy behaviour against synthetic test cases — it tells you whether specific scenarios produce the expected outcome. Testing happens before deployment; dry-run happens during staged rollout. Both are essential.

Effective policy tests cover three categories: positive tests (verify that permitted operations are allowed), negative tests (verify that restricted operations are denied), and boundary tests (verify behaviour at condition thresholds, e.g. exactly at the payment limit). A policy without tests is a policy you cannot confidently change — any modification might break existing behaviour in ways you discover only when agents fail in production.

Intercept includes a built-in test runner that evaluates policies against YAML test fixtures. Each test case defines a synthetic tool call (server, tool, arguments) and the expected outcome (allow, deny, or log). The test runner executes the full policy evaluation pipeline against each test case and reports pass/fail results. Tests can be run locally during development, in CI/CD pipelines before deployment, and as part of policy review processes. The test format is YAML, consistent with the policy format, keeping the learning curve minimal.