CTFL-v4 Testing Throughout the SDLC Practice Question
A system is being developed using an incremental model. During which testing stage should the team verify that the new increment correctly integrates with the existing system functionality?
⚠ Common exam trap
Test-takers often confuse component integration testing with system integration testing, failing to recognize that combining an entire new increment with an existing system requires system integration testing.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
System integration testing.
In an incremental model, each new increment must be integrated into the existing stable codebase. Integration testing is the specific activity that validates the interfaces and communication between the new parts and the old ones. This ensures that the system as a whole remains functional, preventing regressions and ensuring that the newly added features are correctly supported by the existing architecture.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Acceptance testing of the new increment only.
Why it's wrong here
Acceptance testing focuses on the business functionality of the new features. It does not look at the integration points between the increment and the existing system. Relying solely on acceptance testing could leave hidden architectural flaws in the system's integration points that would only appear later.
- ✓
System integration testing.
Why this is correct
System integration testing is the most appropriate stage to verify that the new increment, when combined with the existing codebase, maintains overall system integrity. It ensures that the interfaces are correctly connected and that the system as a whole functions as expected after the addition.
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Unit testing of the new increment.
Why it's wrong here
Unit testing only covers the components within the increment itself. It does not test the dependencies or the communication path between the new code and the rest of the existing application. Therefore, it is insufficient for verifying the success of the integration between the new and old parts.
- ✗
Static testing of the design documents.
Why it's wrong here
Static testing should have been done when the increment was planned. While it helps catch design flaws early, it cannot verify the actual integration at the code level. Once the increment is implemented, dynamic integration testing is required to confirm the work was done correctly and successfully.
About these practice questions
Courseiva writes every CTFL-v4 question from scratch — 144 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISTQB exam blueprint
This CTFL-v4 practice question is part of Courseiva's free ISTQB certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CTFL-v4 exam.