SDLC, STLC and test levels
SDLC (Software Development Life Cycle) — the software lifecycle: requirements → design → development → testing → deployment → maintenance. Models: Waterfall, V-Model, Agile/Scrum (most asked about).
STLC (Software Testing Life Cycle) — the testing process's own cycle:
- Requirement analysis
- Test planning
- Test case design
- Environment setup
- Test execution
- Test closure
| Test level | What it checks | Who does it |
|---|---|---|
| Unit testing | Individual functions/components | Developers |
| Integration testing | Interaction between modules | Developers/QA |
| System testing | The whole system against requirements | QA |
| Acceptance testing (UAT) | Fit to business needs | Customer/business side |
A frequent interview question: "When does QA get involved in Agile?" Answer: from the start of the sprint — analysing requirements in refinement, asking questions, helping shape acceptance criteria (shift-left).