Testing

Execution Workflow

1. Choose the right client shape first: TestClient, AsyncTestClient, create_test_client, or subprocess live-server helpers.
2. Build fixtures with deterministic configuration, dependencies, and lifecycle boundaries.
3. Isolate external I/O with injected fakes or mocked dependencies instead of monkeypatching internals.
4. Assert full contracts: status code, body, headers, cookies, side effects, and failure payload shape.
5. Cover error paths deliberately, including validation failures, app-level exception mappings, event-listener failures, layered override precedence, and schema/docs regressions.

Core Rules

• Keep tests deterministic in time, randomness, and I/O.
• Use AsyncTestClient when tests, fixtures, and app resources must share the same event loop.
• Use create_test_client for isolated handler tests or small app subsets.
• Prefer dependency injection and fake services over patching transport-layer code.
• Assert stable error contracts, not just that an exception occurred.
• Reset overrides and fixture state between tests.
• Use live-server subprocess helpers when the in-process client cannot emulate the transport correctly.