When a deviation from specified or expected behaviour is visible to end-user, this is called
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an error
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a fault
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a failure
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a defect
In software testing terminology, a failure is when the system deviates from expected behavior during execution - it's the visible symptom to the end-user. A fault is the defect in code that causes the failure. An error is a human mistake that leads to a fault. A defect is often used interchangeably with fault.
To answer this question, you need to understand the definitions of each term. Let's go through each option to understand why it is correct or incorrect:
Option A) An error - An error refers to a human mistake or incorrect action that leads to a deviation from the desired or expected behavior. It may or may not be visible to the end-user. Therefore, this option is incorrect.
Option B) A fault - A fault refers to a defect or malfunction in a system or component that causes it to deviate from its expected behavior. It is typically not visible to the end-user. Therefore, this option is incorrect.
Option C) A failure - A failure refers to a situation where a system or component does not perform its intended function or deliver the expected results. It is visible to the end-user and indicates that the system is not working correctly. Therefore, this option is correct.
Option D) A defect - A defect refers to a flaw or imperfection in a system or component that causes it to deviate from its expected behavior. It may or may not be visible to the end-user. Therefore, this option is incorrect.
The correct answer is C) a failure. This option is correct because when a deviation from specified or expected behavior is visible to the end-user, it is referred to as a failure.