During which phase of a waterfall approach does testing of program outputs occur after it has been developed?

During the Testing phase of the waterfall approach, formal testing of the program outputs occurs after the development of the software. This phase is critical because it is specifically dedicated to evaluating the system's functionality, performance, and reliability. The main goal is to ensure that the program meets the specified requirements outlined in earlier phases, such as the Analysis and Design phases. Testing involves various activities like unit testing, integration testing, and system testing, where different components and the overall system are systematically validated against the original requirements.

The emphasis on this phase ensures that any defects or issues can be identified and rectified before the software is deployed. Therefore, the Testing phase serves as a safeguard for quality assurance, confirming that the product is ready for implementation and meets the end users’ needs.