Vue Storefront Middleware ↔ commercetools: Testing Cart/Checkout Flows Without Production Credentials

Integration Boundary

Vue Storefront's commercetools middleware (@vsf-enterprise/commercetools-api) requires valid projectKey, clientId, and clientSecret at startup; there is no configuration flag to enable a mock adapter.

Constraints

• commercetools sandbox credentials come from a per-developer trial project that expires after 60 days of inactivity.
• Community mock libraries (e.g., commercetools-mock) do not fully replicate cart discount calculation, inventory reservation, or B2B approval flows.
• The middleware's createApiClient() is instantiated once per process; replacing it with a test double is not documented or supported.

Open Questions

1. Should teams invest in a contract-testing layer (Pact) between the middleware and commercetools, or maintain a dedicated trial project per developer?
2. Is there a supported pattern for injecting a mock HTTP client into the middleware without forking @vsf-enterprise/commercetools-api?
3. How do CI pipelines reliably run cart/checkout integration tests when sandbox credentials rotate?