CTFL_Syll_4.0 Exam Dumps : ISTQB Certified Tester Foundation Level (CTFL) v4.0

In the given state transition diagram, we need to identify the minimum number of test cases required to cover every unique sequence of exactly 4 states/3 transitions starting and ending in the "Inactive" state.

The states are:

Inactive

Active

Alert Mode

Alarm bell rings

Inactive -> Active -> Inactive -> Active -> Inactive

Sequence: Press Button, Enter PIN, Press Button, Enter PIN

Inactive -> Active -> Alert Mode -> Inactive

Sequence: Press Button, Sensor Activated, Enter PIN

Inactive -> Active -> Alert Mode -> Alarm bell rings -> Inactive

Sequence: Press Button, Sensor Activated, Timeout expired, Press Button

Test Case Analysis:These sequences cover every unique combination of exactly 4 states and 3 transitions starting and ending in the "Inactive" state.

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Comprehensive and Detailed Explanation From Exact Extract:

This question applies theState Transition Testingtechnique.

Let’s evaluateOption Dstep-by-step:

NORMAL MODE → DEGRADED MODE:✅Valid on“FAILURE DETECTED”

DEGRADED MODE → NORMAL MODE:✅Valid on“ALL FAILURES CLEARED”

NORMAL MODE → DIAGNOSTIC MODE:✅Valid on“SELF DIAGNOSTIC INITIATED”

DIAGNOSTIC MODE → DEGRADED MODE:❌Invalid– there isno defined transitionfrom DIAGNOSTIC MODE directly to DEGRADED MODE.

According to the state diagram, DEGRADED MODE can only be entered:

From NORMAL MODE (on FAILURE DETECTED), or

Not from DIAGNOSTIC MODE at all.

This violates the rule:

“State transition testing uses a model where test cases are designed to execute valid and invalid transitions.”

(ISTQB CTFL Syllabus v4.0, Section 4.2.4 – State Transition Testing, Page 40)

Thus, OptionDcontains aninvalid transition, making it the correct answer.