adapter-contract-testing

Contract testing prevents adapter drift by exercising the same abstract test contract through both real adapters and simulators. You enforce one abstract contract class with two concrete test subclasses to validate consistent behavior and prevent mock implementations from evolving away from real APIs.

The canonical contract testing pattern for port adapters requires one abstract contract class, two concrete test subclasses, and no simulator-only tests. This structure guarantees cross-implementation coverage and enforces consistent behavior validation across all adapter implementations.

To set up pytest contract tests for multiple adapter implementations, create an abstract contract test class defining the shared behaviors, then subclass it with two concrete test classes that run against the real adapter and simulator respectively to validate cross-implementation coverage.

Simulator-only tests should be avoided because they break the contract testing pattern and allow simulators to drift from real adapter behavior. The pattern mandates one abstract contract exercised by both implementations to guarantee regression safety and cross-implementation coverage.

Yes, contract testing supports pre-seeded data validation across port adapters. The contract enforces clear rules for pre-seeded data and cross-implementation coverage, ensuring adapters like SmoobuGateway, RequestMemory, and ReservationCache validate behavior consistently.

The abstract contract test class limits you to enforcing exactly one contract with two concrete test subclasses and no simulator-only tests. This rigidity ensures coverage but requires all port adapters and simulators to conform strictly to the shared contract rules for pre-seeded data.