Exam CTAL-TA_V4.0 Topic 1 Question 26 Discussion

Actual exam question for ISQI's CTAL-TA_V4.0 exam
Question #: 26
Topic #: 1
A simple DVD player is described in the following state transition diagram:
States shown in the diagram:

All round trips are feasible, even those that do not start at OFF. How many test cases will be needed for complete round-trip coverage?

Suggested Answer: B Vote an answer

The correct answer is B , because complete round-trip coverage requires every feasible round trip in the state model to be covered, not only those that start from the initial OFF state. CTAL-TA v4.0 explicitly includes state transition testing with N-switch and round-trip coverage as the focus of its state transition topic. A round trip is a path that starts and ends in the same state, normally without repeating an intermediate state.
The feasible round trips are:
* OFF # PLAY # OFF
* PLAY # OFF # PLAY
* OFF # REC # OFF
* REC # OFF # REC
* REC # REC PAUSE # REC
* REC PAUSE # REC # REC PAUSE
* PLAY # PLAY PAUSE # PLAY
* PLAY PAUSE # PLAY # PLAY PAUSE
* OFF # REC # REC PAUSE # OFF
* REC # REC PAUSE # OFF # REC
* REC PAUSE # OFF # REC # REC PAUSE
That gives 11 round trips. The warning in the question is important: if only OFF-starting round trips were counted, the answer would be too low. Option A overcounts by adding a non-modeled or duplicate round trip.
Options C and D miss feasible non-OFF-starting round trips. Reference: CTAL-TA v4.0, Section 3.2.2 State Transition Testing , round-trip coverage.

by Dennis at Jul 20, 2026, 05:44 AM

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