CTAL-TA v4.0: Certified Tester Advanced Level Test AnalystDemo

By ISTQB · Question Mode

QuestionQ39

Test Analysis and Test Design

A credit risk scoring system accepts two integer inputs, L and E, representing credit scores calculated by two independent systems. The system assesses credit risk using the following business logic:

IF L >= 50 OR E >= 50 THEN the risk is high

IF L <= 49 AND E <= 49 THEN the risk is low

Question Image

The figure displays a section of the input domain. Points in the gray area are part of the “high risk” equivalence partition, and points outside it are part of the “low risk” equivalence partition. The lines indicate the closed boundary of the “high risk” equivalence partition.

You use domain-based testing to verify the correct implementation of the above requirement. The test set contains the five black points in the figure: (L=48, E=48), (L=49, E=49), (L=49, E=50), (L=50, E=49), and (L=54, E=53).

What level of RELIABLE domain coverage does this set of test points achieve?

  • A 50%
  • B 62.5%
  • C 87.5%
  • D 100%
Explanation

Reliable domain coverage requires an ON, OFF, IN, and OUT point for every border defined by a closed inequality. The two borders, L >= 50 and E >= 50, therefore have eight coverage items. The test points provide all four types for each border: the two threshold points are ON, (49,49) is OFF for both, (48,48) is OUT for both, and points in the high-risk partition supply IN coverage. Thus all eight coverage items are covered.

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