Discuss ISTQB ISTQB-CTFL Exam Topic 1 Question 3

A program got 100% decision coverage in a test. Which of the following statements is then guaranteed to be true?

AEvery executable statement Is covered.

BEvery output equivalence class has been tested.

CEvery input equivalence class has been tested.

DThe 'dead' code has not been covered.

Suggested Answer: A

If a program got 100% decision coverage in a test, then it is guaranteed that every executable statement is covered. Decision coverage (also known as branch coverage) is a type of structural coverage (also known as white-box coverage) that measures how many decision outcomes have been exercised by a test suite. A decision outcome is a possible result of a decision point (such as an if-then-else statement) in a program's code. Decision coverage requires that each decision point has both true and false outcomes executed at least once by a test suite. Decision coverage implies statement coverage, which is another type of structural coverage that measures how many executable statements have been executed by a test suite. Statement coverage requires that each executable statement is executed at least once by a test suite. Therefore, if a program got 100% decision coverage in a test, then it also got 100% statement coverage in a test, which means that every executable statement is covered. The other options are not guaranteed to be true if a program got 100% decision coverage in a test. Every output equivalence class has been tested and every input equivalence class has been tested are not guaranteed to be true if a program got 100% decision coverage in a test, because equivalence classes are based on functional requirements or specifications, not on code structure or logic. Equivalence classes are used in specification-based testing (also known as black-box testing), which is a type of testing that does not consider the internal structure or implementation of the system under test. Decision coverage is used in structure-based testing (also known as white-box testing), which is a type of testing that considers the internal structure or implementation of the system under test. Therefore, achieving 100% decision coverage does not imply achieving 100% equivalence class coverage. The ''dead'' code has not been covered is not guaranteed to be true if a program got 100% decision coverage in a test, because dead code (also known as unreachable code) is code that can never be executed due to logical errors or design flaws. Dead code can reduce readability and maintainability of the code, as well as increase complexity and size. Decision coverage does not account for dead code, as it only considers the decision outcomes that are possible to execute. Therefore, achieving 100% decision coverage does not imply that the dead code has not been covered. Verified Reference:A Study Guide to the ISTQB Foundation Level 2018 Syllabus - Springer, page 36.

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13 comments · newest first

Nida 11 months ago

B and C are definitely not guaranteed with just decision coverage.

Johana 11 months ago

Yeah, I thought decision coverage was enough to ensure all paths were tested.

Nancey 11 months ago

Wait, so dead code can still exist even with full decision coverage?

Annice 11 months ago

Totally agree, just because decisions are covered doesn't mean every line is hit.

Eliseo 12 months ago

100% decision coverage doesn't mean all statements are covered.

Josue 12 months ago

I’m leaning towards D because if we have 100% decision coverage, it doesn’t necessarily mean dead code is covered.

Crista 12 months ago

I feel like we discussed equivalence classes in class, but I can't recall if decision coverage ensures those are tested.

Ulysses 1 year ago

I think I saw a similar question where decision coverage didn't imply all statements were covered. Maybe it's A that's wrong?

Silva 1 year ago

I remember decision coverage means all decision points were tested, but I'm not sure if that guarantees every statement was executed.

Denny 1 year ago

Hmm, I'm a bit unsure about this one. Interoperability testing is important, but I'm not sure which technique would be most appropriate here. I'll have to think it through carefully.

Justine 1 year ago

Hmm, I'm a bit unsure about this one. I know we need to align the business perspective with the information concepts, but I'm not sure which one is the best fit. I'll have to think this through carefully.

Fidelia 1 year ago

I'm feeling pretty confident about this one. The key is recognizing that the question is specifically asking about the customer's responsibilities in an OpenShift on IBM Cloud environment. Option C, recovering worker nodes, seems to be the task that aligns best with that.

Amie 1 year ago

I have a vague recollection of RAID configurations; could it be possible that OSS uses other methods as well for that reliability?

ISTQB-CTFL Exam - Topic 1 Question 3 Discussion