1. Introduction
This question tests your understanding of statement coverage and how multiple test cases contribute to the combined coverage of a test suite.
이 문제는 문장 커버리지(statement coverage) 개념과 여러 테스트 케이스가 결합될 때 커버리지가 어떻게 계산되는지를 묻는 문제입니다.
2. Given Information
- T1 achieves 40% statement coverage
- T2 achieves 65% statement coverage
The question asks: Which statement must be necessarily true?
T1은 40%, T2는 65% 문장 커버리지를 달성했다고 할 때 반드시 참이어야 하는 문장을 고르는 문제입니다.
3. Option-by-Option Analysis
a) The combined test suite achieves 105% coverage
Not correct. Coverage cannot exceed 100% by definition.
커버리지는 최대 100%이므로 105%는 불가능합니다.
b) There exists at least one statement that must have been executed by both T1 and T2
Correct.
If T1 and T2 covered completely disjoint sets of statements, the combined coverage would be:
40% + 65% = 105% (impossible)
Therefore the two tests must overlap by at least 5%.
T1과 T2가 서로 겹치지 않았다면 합쳐서 105% 커버리지가 되는데 이는 불가능합니다. 따라서 최소한 5%는 두 테스트가 공통으로 실행한 문장이 존재해야 합니다.
c) At least 5% of statements are non-executable
Not correct. Statement coverage does not give information about non-executable code.
문장 커버리지는 실행 불가능 코드의 존재 여부를 말해주지 않습니다.
d) The combined suite achieves full branch coverage
Not correct.
Full statement coverage does not imply full branch coverage.
문장 커버리지가 높아도 분기(branch) 커버리지가 보장되지는 않습니다.
4. Correct Answer
✅ Correct Answer: b)
Because 40% + 65% = 105%, and coverage cannot exceed 100%, there must be at least overlapping executed statements.
두 테스트가 완전히 독립적일 수 없기 때문에 b)가 반드시 참입니다.
5. Summary
- Coverage percentages from different tests can overlap.
- If simple addition exceeds 100%, overlap is guaranteed.
- Statement coverage does not imply branch coverage.
- No information about non-executable code can be inferred.
문장 커버리지의 합이 100%를 넘으면 반드시 두 테스트가 공통 문장을 실행한 것입니다. FL-4.3.1
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