Error Guessing – What Is NOT Anticipated
1. Introduction
In the ISTQB Foundation Level syllabus, error guessing is classified as an experience-based test technique.
It focuses on anticipating errors, defects, and failures based on the tester’s experience with similar systems and common problem patterns.
ISTQB에서 오류 추정(Error guessing)은 테스터의 경험과 직관을 활용하여 발생 가능성이 높은 오류, 결함, 실패를 예측하는 경험 기반 테스트 기법입니다.
이 문제는 오류 추정으로 예측할 수 없는 대상이 무엇인지 묻습니다.
2. Practice Question
❓ Question
Which of the following is NOT anticipated by the tester while applying error guessing?
- a) The developer misunderstood the formula in the user story for calculating the interest
- b) The developer wrote “FA = A*(1+IR^N)” instead of “FA = A*(1+IR)^N” in the source code
- c) The developer missed the seminar on new compound interest rate legislation
- d) The accuracy of the interest calculated by the system is not precise enough
✅ Correct Answer: c)
3. Explanation
✔ c) Developer missed the seminar — Correct
Error guessing is about anticipating errors, defects, and failures in the software based on experience.
Option c describes a root cause related to training or organizational issues.
Root causes are:
- Not directly visible in the software
- Often outside the tester’s observation
- Difficult or impossible to anticipate using testing techniques
Therefore, this situation is not anticipated when applying error guessing.
c는 개발자의 교육 이력이라는 결함의 근본 원인(root cause)에 해당합니다.
오류 추정은 오류·결함·실패를 예측하는 기법이지, 개발자의 교육 여부와 같은 근본 원인을 예측하는 기법은 아니므로 정답입니다.
❌ a) Misunderstood formula — Incorrect
This is an example of anticipating a developer error.
Testers often guess that developers may misunderstand complex formulas or business rules.
요구사항의 수식을 잘못 이해하는 것은 전형적인 개발자 오류로, 오류 추정의 대상입니다.
❌ b) Incorrect formula in source code — Incorrect
This represents a defect in the implementation.
Error guessing commonly anticipates mistakes such as:
- Wrong operators
- Incorrect precedence
- Missing parentheses
괄호 누락이나 연산자 오류는 경험적으로 자주 발생하는 결함이므로 오류 추정으로 충분히 예측 가능합니다.
❌ d) Interest calculation not accurate enough — Incorrect
This is an example of anticipating a failure, where the system produces an unacceptable result.
Based on experience with similar systems, testers may expect accuracy or precision issues.
계산 정확도 부족은 실행 결과에서 나타나는 실패로, 오류 추정의 대상이 됩니다.
4. Summary Table
| Option | Represents | Anticipated by Error Guessing? | 구분 |
|---|---|---|---|
| a | Error (developer misunderstanding) | ✔ Yes | 오류 |
| b | Defect (wrong formula) | ✔ Yes | 결함 |
| c | Root cause (training issue) | ✖ No | 근본 원인 |
| d | Failure (incorrect result) | ✔ Yes | 실패 |
5. Final Takeaway
For the ISTQB exam, remember this distinction:
Error guessing anticipates errors, defects, and failures, but not underlying root causes such as training or organizational issues.
시험 대비 핵심 문장입니다.
오류 추정은 오류·결함·실패를 예측하는 기법이며, 교육 부족과 같은 근본 원인은 예측 대상이 아니다.
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