Testing in an SAP system under cloud environments:

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1. Unit Testing
Also called: Component Testing / Program-Level Validation
Conducted by ABAP developers, functional consultants, or key technical experts to verify the correctness of individual programs, Fiori apps, custom objects, or reports in isolation.
In SAP S/4HANA Cloud (Public & Private), this includes OData services, CDS views, and custom extensions built in SAP Business Technology Platform (BTP).

2. Integration Testing
Also called: End-to-End Process Validation / Cross-Module Testing
Confirms that interlinked processes across modules (e.g., FI ↔ MM ↔ SD ↔ PP) function seamlessly without data or process breaks.
In cloud environments, also covers integration with external systems (Ariba, SuccessFactors, Concur, 3rd-party APIs) using SAP Cloud Integration Suite.

3. Regression Testing
Also called: Change Impact Testing / Functional Stability Check
Ensures that existing functionality remains unaffected after configuration changes, upgrades, hotfixes, or quarterly SAP S/4HANA Cloud releases.
Often automated in cloud environments using SAP Cloud ALM, CBTA, or Tricentis Test Automation.

4. User Acceptance Testing (UAT)
Also called: Business Validation Testing / Operational Sign-Off
Conducted by business process owners and key users to verify that real-life business scenarios (not just test cases) run as expected.
In cloud projects, UAT often aligns with Fit-to-Standard workshops to confirm process readiness before go-live.

5. Performance Testing
Also called: Load & Stress Testing / Scalability Testing
Evaluates system responsiveness, stability, and throughput under peak load conditions.
In cloud, this may involve testing Fiori app response times, background job execution, API throughput, and SAP BTP extension performance.

6. Security Testing
Also called: Authorization Validation / Access Control Testing
Verifies roles, authorizations, segregation of duties (SoD), and access restrictions according to business compliance policies.
In S/4HANA Cloud, this includes Business Role Templates, Identity Authentication Service (IAS), and Identity Provisioning Service (IPS) configurations.

7. Build Verification Testing
Also called: Sanity Check
A quick, high-level validation to confirm that critical system functions are working after a new transport, upgrade, or cloud release before deeper testing.
In public cloud, this is crucial post-release due to SAP’s quarterly upgrade cycles.

8. Data Migration Testing
Also called: Data Conversion Validation / Legacy-to-Cloud Data Verification
Ensures complete, accurate, and loss-free data transfer from legacy systems to SAP S/4HANA via tools like SAP Migration Cockpit or Data Services.
Covers data cleansing, mapping validation, reconciliation reports, and post-load functional validation to ensure business processes work with migrated data.