Which levels of testing are typical for a FOSSE change, and what do they validate?

• A. Unit, integration, SIT, UAT, regression, and performance/load testing
• B. Unit and performance
• C. Only unit
• D. Acceptance testing only

Answer: (A)

Testing a FOSSE change is about validating all the layers where the change can have impact, from how individual components behave to how the entire front-office workflow performs in real conditions. Unit testing checks that each small piece of code works on its own, proving the correctness of the building blocks. Integration testing then looks at how those pieces work together and whether the interfaces between modules pass data and control as expected. System Integration Testing extends that to end-to-end business processes across the integrated system, ensuring the whole front-office flow runs smoothly in the test environment. User Acceptance Testing brings in the actual users to confirm the change meets business requirements and is usable in real-world scenarios. Regression testing repeats the existing test suite to verify that new changes haven’t broken previously working functionality. Performance or load testing examines how the system behaves under typical and peak workloads, checking response times and resource usage.

A comprehensive FOSSE change typically goes through all these levels because the change can affect multiple components, interfaces, and business processes, not just a single unit of code. Limiting testing to one or two levels risks missing critical issues in real-world usage or under load, which is why the full set of levels is standard.