1. Question
Let the branch coverage metric be defined as: BCov = (X / Y) × 100%
What do X and Y represent in this formula?
- a) X = number of decision outcomes exercised by the test cases
Y = total number of decision outcomes in the code - b) X = number of conditional branches exercised by the test cases
Y = total number of branches in the code - c) X = number of branches exercised by the test cases
Y = total number of branches in the code - d) X = number of conditional branches exercised by the test cases
Y = total number of decision outcomes in the code
✅ Correct Answer: c)
2. Understanding Branch Coverage
Branch Coverage is a white-box testing metric that measures whether every possible branch (i.e., every possible control flow transfer) has been executed at least once.
분기 커버리지(Branch Coverage)는 프로그램의 모든 “분기(브랜치)”를 최소 한 번 실행했는지 측정하는 화이트박스 커버리지 기법입니다.
✔ A branch = any transfer of control
- Conditional branch → from decision outcomes (IF, WHILE, FOR)
- Unconditional branch → straight-line control flow (next statement)
즉, 분기에는 조건 분기뿐 아니라 무조건 분기(unconditional)도 포함됩니다.
3. Why Option c) Is Correct
BCov = (X / Y) × 100%
- X = number of branches executed by tests
- Y = total number of branches in the code
This matches the ISTQB definition: Branch coverage = (executed branches) / (all branches)
ISTQB 공식 정의와 동일하게 X = 실행된 분기 수, Y = 전체 분기 수이므로 c)가 정답입니다.
4. Why the Other Options Are Incorrect
a) Counts only decision outcomes → ❌ excludes unconditional branches
결정 결과만 포함하므로 무조건 분기를 포함하지 않아 틀림.
b) X counts only conditional branches → ❌ incomplete
조건 분기만 세면 전체 분기(branch)의 개념과 다름.
d) Both X and Y ignore unconditional branches → ❌ incorrect basis
둘 다 조건 분기만 고려하므로 잘못된 분기 정의.
5. Summary
- Branch = any control flow change (conditional + unconditional)
- Branch Coverage = executed branches / total branches
- Therefore: option c) is correct
분기 커버리지는 “실행된 모든 분기 ÷ 전체 분기”이므로 정답은 c)입니다. FL-4.3.2
Related: More ISTQB Posts