Q11 of 38 · Manual & exploratory
What is the test life cycle (STLC) and how does it differ from SDLC?
Short answer
Short answer: STLC describes the testing-specific phases — requirement analysis, test planning, design, environment setup, execution, and closure. SDLC is the broader software development cycle. STLC sits inside SDLC, running in parallel with development from the requirements phase onwards.
Detail
The Software Development Life Cycle (SDLC) is the umbrella process: requirements, design, development, testing, deployment, maintenance. The Software Testing Life Cycle (STLC) is the test-specific subset, with its own phases:
- Requirements analysis — review specs from a testability perspective. What's testable? What's ambiguous?
- Test planning — strategy, scope, schedule, resourcing, environment needs, exit criteria.
- Test case design — derive cases from requirements (using EP, BVA, decision tables), prioritise, peer review.
- Environment setup — staging environments, test data, mocks for third-party dependencies.
- Test execution — run cases, log defects, retest fixes, regression-test.
- Test closure — exit report, defect metrics, lessons learned, regression suite handoff.
STLC starts during the SDLC requirements phase (testers reviewing the spec), runs in parallel with development, intensifies during the testing phase, and continues through maintenance (regression tests on bug fixes).
Most modern teams running agile or DevOps don't follow STLC as a sequential waterfall — phases overlap and iterate per sprint. But the STLC vocabulary remains useful for organising what testing activities exist and when.