Software Engineering and System Development Life Cycle
What is tested
Software Engineering and System Development Life Cycle covers how software is planned, built, tested and maintained. Expect phase ordering, model selection, requirement statements, testing levels and maintenance categories.
Core rules
- SDLC phases: requirement analysis, feasibility study, design, coding, testing, deployment and maintenance. These are logical phases; models may overlap or repeat them.
- Waterfall is sequential and suits stable, well-understood requirements. Iterative/incremental models deliver in cycles. Spiral emphasises risk analysis.
- An SRS states what the system must do, not how it will be coded. It should be clear, complete and testable.
- Testing levels: unit, integration, system and acceptance. Black-box testing checks behaviour from inputs/outputs; white-box testing uses code structure.
- Maintenance includes corrective, adaptive, perfective and preventive work.
Worked example
A school wants a result-processing system, but the grading rules may change each year. Choose an iterative model rather than waterfall: each cycle can deliver a working module and incorporate the new rules after feedback. Waterfall would freeze requirements early, making later grading changes expensive. The reasoning is based on requirement stability and risk, not on team size alone.
Traps
Testing finds defects; debugging fixes them. Maintenance is not only bug repair. Verification asks whether the product was built right; validation asks whether the right product was built. Do not put design decisions such as table schemas into an SRS unless they are genuine constraints.