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

Direct answer

There is no supported configuration flag in @vsf-enterprise/commercetools-api that switches the middleware to a mock commercetools adapter, and replacing createApiClient() with a test double is undocumented. Do not fork the package just to run cart or checkout tests. Test against a non-production commercetools project using short-lived OAuth credentials, or drive the SDK through a local HTTP proxy that returns recorded cart/checkout responses.

Likely explanation versus confirmed facts

Likely explanation

The middleware validates projectKey, clientId, and clientSecret when the API client is constructed, and it creates that client once per process. Because no mock or adapter option is exposed in the configuration schema, tests cannot simply flip a mode flag to bypass commercetools.

Confirmed facts

• commercetools carts and orders are standard HTTP API resources reachable with OAuth client-credentials or anonymous-session authentication.
• Community mock libraries do not fully reproduce cart discount calculation, inventory reservation, or B2B approval flows, so passing mock tests is not evidence of production checkout behavior.
• Pact-style contract testing can verify request and response shapes at the integration boundary, but it cannot simulate commercetools business logic such as discounts or inventory reservation.

Recommended steps

1. Create a non-production commercetools project for testing and generate API client credentials with the least scope needed for carts and orders.
2. In CI, fetch a short-lived OAuth access token before each test run and inject clientId and clientSecret as masked secrets. Do not commit or long-store access tokens.
3. Point the commercetools SDK base URL at a local test proxy or recorded-response server when you want to avoid live calls. Verify the proxy returns the same resource shapes your frontend expects.
4. Isolate tests that depend on cart discounts, inventory reservation, or B2B approval. Run those only against the non-production sandbox; do not rely on a mock library for those behaviors.
5. Use Pact only for regression checks on request/response contracts, not as a substitute for sandbox behavioral tests.

Practical verification

• Inspect the installed package's configuration schema and entrypoint for mock, mode, or adapter flags. Absence of such flags supports the no-mock-mode assumption for your release.
• Attempt to initialize the client with placeholder credentials in a non-production process and confirm startup fails before any cart call.
• From Merchant Center, create a non-production project, generate credentials, request an OAuth token, and call the carts endpoint to confirm the endpoint pattern.
• Run a cart create and order create call against the local proxy with recorded responses and assert the application handles them without production credentials.

Missing diagnostic detail

I need the exact Vue Storefront major version and the installed @vsf-enterprise/commercetools-api package version. Client instantiation, configuration keys, and any override options vary by release, and that determines whether a baseURL override or constructor option is available without forking.

Unverified: The 60-day trial inactivity expiry is reported by the questioner but not confirmed here; commercetools account lifecycle terms are release-dependent.