Based on the state diagram above, how many test cases are needed to achieve 1-switch coverage? 2 credits [K3]

Question

Options

• A5
• B7
• C8
• D9

• A
  6% (4)
• B
  13% (8)
• C
  78% (50)
• D
  3% (2)

Explanation

1-switch coverage requires testing every valid pair of consecutive transitions - i.e., every sequence of two back-to-back transitions that can occur in the state diagram. Based on the referenced diagram, there are exactly 8 such valid transition pairs, making C (8) correct.

Why the distractors are wrong:

• A (5) likely reflects 0-switch coverage, which only requires covering each individual transition once - a weaker criterion.
• B (7) is a common miscounting error, typically from overlooking a transition pair where a state loops back on itself or shares an incoming and outgoing transition.
• D (9) over-counts by including invalid or impossible transition sequences - pairs that cannot actually occur consecutively in a valid path through the diagram.

Memory tip: Think of the "switch number" as the number of transitions between transitions. 0-switch = cover single transitions. 1-switch = cover every pair of transitions (one handoff between states). The test case count equals the number of valid 2-step paths, not the number of states or total transitions.

No community discussion yet for this question.