Final answer:
Software is tested during the implementation phase of the SDLC, where functions are evaluated to ensure they work as intended. This phase typically includes building prototypes, testing, and refining the software.
Step-by-step explanation:
During the Software Development Life Cycle (SDLC), software is tested to ensure that each function works as intended primarily in the implementation phase. Testing is a crucial activity that occurs after the design phase where prototypes are developed. The main purpose of the implementation phase is to translate the detailed design into code and test the software to identify any issues or areas for improvement.
Essentially, once a prototype is built, the software must undergo rigorous testing and evaluation to make sure all the constraints are met and the functions perform acceptably. This phase often involves many iterations of testing and refinement. If a design shows significant issues or does not meet the necessary criteria, it may be necessary to revise the design or return to an earlier phase of the SDLC.