Functional vs Non-Functional Testing (Exam D – Question 13)
1. Introduction
In the ISTQB Foundation Level syllabus, functional testing focuses on what the system does and whether it behaves according to specified requirements.
This question checks whether you can distinguish functional testing from different types of non-functional testing.
ISTQB에서 기능 테스트(Functional testing)는 시스템이 무엇을 하는지, 즉 기능적 요구사항을 올바르게 수행하는지를 확인합니다.
이 문제는 기능 테스트와 비기능 테스트를 정확히 구분할 수 있는지를 묻습니다.
2. Practice Question
❓ Question
Which of the following tests is MOST likely to be performed as part of functional testing?
- a) The test checks that the sort function puts the elements of the list or array in ascending order
- b) The test checks whether the sort function completes sorting within one second of starting
- c) The test checks how easily the sort function can be changed from sorting ascending to sorting descending
- d) The test checks that the sort function still functions correctly when moved from a 32-bit to a 64-bit architecture
✅ Correct Answer: a)
3. Explanation
✔ a) Check sorting in ascending order — Correct
This test verifies that the sort function produces the correct output according to its functional specification.
Confirming that a list or array is sorted in ascending order is a direct check of functional correctness.
이 테스트는 정렬 기능이 요구된 대로 오름차순 결과를 생성하는지를 확인합니다.
이는 기능 요구사항의 정확성을 검증하는 대표적인 기능 테스트입니다.
❌ b) Check completion within one second — Incorrect
This test evaluates whether the function meets a performance requirement.
Performance efficiency is a type of non-functional testing, not functional testing.
1초 이내에 완료되는지를 확인하는 것은 성능(Performance) 요구사항을 검증하는 테스트입니다.
성능 테스트는 비기능 테스트에 해당합니다.
❌ c) Check ease of modification — Incorrect
This test focuses on how easily the code can be changed, which relates to maintainability.
Maintainability is a non-functional quality characteristic.
정렬 방식 변경이 쉬운지를 확인하는 것은 유지보수성(Maintainability) 평가입니다.
유지보수성은 비기능 품질 특성입니다.
❌ d) Check behavior on different architecture — Incorrect
This test checks whether the function works correctly in a different technical environment.
This relates to portability, which is also a non-functional quality characteristic.
32비트에서 64비트 환경으로 옮겨도 동작하는지는 이식성(Portability) 테스트입니다.
이식성 역시 비기능 테스트에 해당합니다.
4. Summary Table
| Option | What is Tested | Functional Testing? | 구분 |
|---|---|---|---|
| a | Correct sorting result | ✔ Yes | 기능 정확성 |
| b | Execution time | ✖ No | 성능 |
| c | Ease of modification | ✖ No | 유지보수성 |
| d | Behavior on different architecture | ✖ No | 이식성 |
5. Final Takeaway
For the ISTQB exam, remember this rule:
Functional testing checks what the system does, while performance, maintainability, and portability are non-functional.
시험 대비 핵심 문장입니다.
기능 테스트는 시스템의 동작 결과를 검증하며, 성능·유지보수성·이식성은 비기능 테스트이다.
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