Which test design technique should be used to cover all possible combinations of the in put conditions?

For withdrawing money tram an Automated Teller Machine (ATM), the following conditions are required:

– The bank card is valid

– The PIN code is correct

– Money is available in the user’s account

The following are some possible interactions between the user and the ATM:

– The entered card is invalid The card is rejected

– The PIN code is wrong The ATM asks for another PIN code

– The requested amount is more than available in the user’s account: The ATM asks for another amount

– The requested amount is available in the user’s account The ATM dispenses the money

Which test design technique should be used to cover all possible combinations of the in put conditions?
A . Use case based testing
B . Decision table
C . Boundary value analysis
D . Equivalence class partitioning

View Answer

Answer: B

Explanation:

A decision table is a technique that should be used to cover all possible combinations of input conditions for withdrawing money from an Automated Teller Machine (ATM). A decision table shows combinations of inputs and/or stimuli (causes) with their associated outputs and/or actions (effects). A decision table consists of four quadrants: conditions (inputs), actions (outputs), condition entries (values) and action entries (results). A decision table can be used to test components that have multiple inputs and outputs that depend on logical combinations of conditions. For example, for testing the ATM, we can identify three input conditions: the bank card is valid, the PIN code is correct, and money is available in the user’s account. We can also identify four output actions: the card is rejected, the ATM asks for another PIN code, the ATM asks for another amount, and the ATM dispenses the money. A decision table can show all possible combinations of these conditions and actions in a systematic way.

Use case based testing is not a technique that can cover all possible combinations of input conditions for withdrawing money from an ATM. Use case based testing is a technique that verifies that a software product or system meets its specified requirements or user stories by executing realistic scenarios or workflows. Use case based testing can be used to test components that have complex or dynamic interactions with users or other systems. For example, for testing the ATM, we can identify several use cases, such as withdraw money, check balance, transfer money, etc. Each use case can have one or more scenarios that describe the steps and outcomes of the interaction. However, use case based testing may not cover all possible combinations of input conditions, as some scenarios may be omitted or overlooked.

Boundary value analysis is not a technique that can cover all possible combinations of input conditions for withdrawing money from an ATM. Boundary value analysis is a technique that tests boundary values between partitions of equivalent data. Boundary values are values at the edge of an equivalence partition or at the smallest incremental distance on either side of an edge. Boundary value analysis can be used to test components that have input values that can be divided into partitions of equivalent data. For example, for testing the ATM, we can identify boundary values for the input amount, such as the minimum and maximum amount allowed by the system or the user’s account. However, boundary value analysis may not cover all possible combinations of input conditions, as some conditions may not have boundary values or may not be related to input values. Equivalence class partitioning is not a technique that can cover all possible combinations of input conditions for withdrawing money from an ATM. Equivalence class partitioning is a technique that divides the input data and output results of a software component into partitions of equivalent data. Each partition should contain data that is treated in the same way by the component. Equivalence class partitioning can be used to test components that have input values that can be divided into partitions of equivalent data. For example, for testing the ATM, we can identify equivalence partitions for the input amount, such as valid amount (within the range allowed by the system and the user’s account) and invalid amount (outside the range allowed by the system or the user’s account). However, equivalence class partitioning may not cover all possible combinations of input conditions, as some conditions may not be related to input values or may have more than two partitions.

Verified Reference: [A Study Guide to the ISTQB® Foundation Level 2018 Syllabus – Springer], Chapter 4, page 34-46.