Quality Assurance Efforts — Incremental Model vs. Agile Development: 19-Soft-A7 Software Development Process, May 2016, Q6

Question 6: Quality Assurance Efforts — Incremental Model vs. Agile Development (10 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

Part a) — QA efforts under the incremental model. QA is organised per increment: each increment's requirements and design are formally reviewed before implementation begins (catching defects while cheapest to fix); as the increment is implemented, unit testing covers each new/changed module; once the increment is code-complete, integration testing verifies it against the already-delivered increments (the Question 1(c) architecture-compatibility risk), followed by a formal system test of the increment's new functionality and a targeted regression test of prior increments' functionality to confirm nothing was broken; a final acceptance review gates the increment's release. The whole cycle (review → unit test → integration test → system/regression test → acceptance) repeats once per increment (Question 3's Team A/B/C QA stages).

Part b) — QA efforts under agile. QA is continuous and embedded in the sprint rather than a separate end-of-increment stage: automated unit tests are written alongside (often before, in TDD) the code they test and run on every commit via continuous integration; pair programming or lightweight peer code review substitutes for a separate formal design review; each story is tested and accepted within the same sprint it is built in (via acceptance-test-driven development against the story's acceptance criteria) rather than waiting for a later dedicated test phase; and the sprint review (customer demo) and retrospective serve as the process-level quality checkpoint, feeding improvements into the very next sprint. The key difference from Part (a) is cadence and integration: agile folds review, test, and regression into every few days of work rather than gating a whole increment at its end, so a defect is caught within roughly one sprint instead of at the end of a multi-week increment.

Concept & Theory

Topic. Software quality assurance activities (reviews, unit/integration/system/regression testing, acceptance) and how their organisation differs between incremental and agile process models.

Key relations. QA activity set is the same in both models — review, test at multiple levels, verify against acceptance criteria — but incremental gates them once per increment while agile embeds them continuously (per commit/per sprint).

Why this works. Recognising the same QA activities recur under both models (just at different cadence and with different tooling — automated CI-driven tests under agile vs. a formal end-of-increment test phase under incremental) avoids the common misconception that agile "skips testing" for speed; it instead compresses the same testing into a much shorter, continuous cycle.

Common pitfall. Describing agile QA as "no formal process" — automated CI pipelines and acceptance-test-driven development are themselves a formal, repeatable QA process, just executed far more frequently than an incremental project's end-of-increment gate.

Source. Pressman, Software Engineering: A Practitioner's Approach, 9th ed., Ch. 22 (Software quality assurance); Sommerville, 10th ed., Ch. 3 (Agile testing), Ch. 8–9 (Software testing).

Question 6 of 8: Quality Assurance Efforts — Incremental Model vs. Agile Development

Question 6: Quality Assurance Efforts — Incremental Model vs. Agile Development (10 marks)