Before promoting an integration to production, it must be verified that all supported payment flows execute correctly end-to-end under conditions that reflect real operational behavior.

End-to-end validation ensures that the integration is not only technically correct at API level, but also functionally complete across the full transaction lifecycle, including asynchronous updates, state transitions, and reconciliation.

Scope of Validation

Validation must cover the complete lifecycle of each supported payment method and flow, including:

• Initial request and response
• Intermediate states (e.g., Pending, InProcessing)
• Final transaction outcome
• Webhook-driven updates
• Status API validation

The objective is to ensure that all system components interact correctly and consistently throughout the full lifecycle.

See F.1 End-to-End Integration Examples for reference execution flows.

Coverage of Payment Methods and Flows

All supported payment methods must be validated under their respective operational flows.

This includes, where applicable:

• Card payments (e.g., AUTH, PURS, two-step flows)
• MB WAY payments
• Multibanco Reference payments
• Recurring and merchant-initiated transactions (MIT)

For each method, validation must include:

• Complete execution from initiation to final state
• Correct handling of asynchronous confirmation
• Proper interaction with external systems or user actions

Validation of Transaction Outcomes

Each flow must be tested across all relevant outcome scenarios.

At minimum, validation must include:

• Successful transactions
• Declined transactions
• Pending or delayed outcomes
• Timeout or indeterminate scenarios

The system must correctly:

• Interpret paymentStatus and returnStatus
• Apply appropriate business logic for each outcome
• Maintain consistent transaction state across all components

See F.3 Success and Error Scenarios for outcome interpretation.

Verification of Asynchronous Behavior

End-to-end validation must explicitly confirm correct handling of asynchronous processing.

This includes:

• Receiving and processing webhook notifications
• Handling delayed or duplicated events
• Confirming final state via the Status API

Validation must ensure that:

• Webhooks trigger the correct internal processing
• Duplicate or out-of-order notifications do not affect correctness
• Final transaction state is always aligned with authoritative sources

See F.6.3 Asynchronous Flow Readiness and F.6.4 Webhook Reliability and Processing Guarantees.

Consistency and State Reconciliation

Validation must confirm that transaction state remains consistent across:

• SPG platform
• Merchant system
• Downstream business processes

This requires verifying that:

• State transitions are valid and correctly applied
• Final states are not overridden or regressed
• Reconciliation between systems produces consistent results

Any discrepancy between systems must be detectable and resolvable.

Validation of Idempotency and Retry Behavior

End-to-end testing must include scenarios involving retries and duplicate operations.

This includes:

• Repeated submission of the same request
• Duplicate webhook notifications
• Retry after timeout or unknown outcome

The system must demonstrate that:

• Duplicate operations do not create additional transactions
• Reprocessing does not alter final outcomes
• Transaction state remains deterministic

See F.6.2 Transaction Idempotency and Duplicate Protection.

Operational and Integration Readiness

Validation must also confirm that the integration behaves correctly under realistic operational conditions.

This includes:

• Handling of network latency and transient failures
• Stability under repeated or concurrent operations
• Correct processing under asynchronous and delayed conditions

The system must demonstrate that it can reliably and consistently sustain the full transaction lifecycle under production conditions.

Go-Live Validation Criteria

An integration is ready for production only when:

• All supported flows have been validated end-to-end
• All relevant outcome scenarios have been tested
• Asynchronous behavior is correctly handled
• Webhook processing is reliable and idempotent
• Transaction state is consistent and reconcilable
• Retry and duplication scenarios are safely handled
• All validation scenarios have been executed under conditions that reflect asynchronous and non-deterministic behavior

Failure to validate any of these aspects may result in incorrect behavior in production.

Final Consideration

End-to-end validation is the final control point before production deployment.

A production-ready integration ensures that:

• All flows execute correctly across their full lifecycle
• All outcomes are correctly interpreted and handled
• All systems remain consistent under real-world conditions

Successful validation confirms not only that the integration works, but that it will continue to work reliably under production constraints.