====== Fault ====== [[dido:99_annexes:annex-b-terms-and-definitions:start|Go up to Terms and Definitions]] ===== Discussion ===== A Fault is a condition of a test object or its operating environment that causes or contributes to a difference between specified and actual behaviour. A Fault differs from a Failure. A Fault is a condition that causes or contributes to incorrect behaviour. A Failure occurs when the test object does not perform a required function or does not satisfy a specified requirement. A Fault also differs from a [[dido:99_annexes:annex-b-terms-and-definitions:t:test_execution_exception|Test Execution Exception]]. A Fault exists within or affects the test object or its operating environment. A Test Execution Exception identifies a condition arising during [[dido:99_annexes:annex-b-terms-and-definitions:t:test_execution|Test Execution]] that differs from a governing requirement, procedure, precondition, sequence, constraint, or expected result. A Fault may exist without producing an immediately observable Failure. The Fault may remain dormant until a particular state, input, interaction, timing condition, or resource condition activates it. ===== Definition ===== a condition of a test object or its operating environment that causes or contributes to a difference between specified and actual behavior ===== Source ===== DIDO-TE controlled definition, informed by the dependability and software-engineering concepts in ISO/IEC/IEEE 24765, //Systems and software engineering — Vocabulary//. ===== Note ===== The governing [[dido:99_annexes:annex-b-terms-and-definitions:t:test_definition|Test Definition]] identifies the specified behavior used to determine whether a Fault causes or contributes to a difference. A Fault may affect state, activity, interaction, processing, timing, input, output, communication, resource use, or another specified operating condition. A Fault may originate within the test object or within a condition governing its operation. ===== Example ===== A Test Definition specifies that a Node SHALL respond to an authorized request within 200 milliseconds. A deliberately introduced communication delay causes the response to exceed that limit. The communication-delay condition is a Fault. The response exceeding 200 milliseconds is the resulting difference between specified and actual behavior. ---- © 2026 Dido Solutions, Inc. and Jackrabbit Consulting, Inc.