Acceptance test planning can begin during the requirements phase because acceptance tests are derived from user needs, business rules, functional requirements, constraints, and acceptance criteria. Software quality engineering encourages early test planning to make requirements measurable, testable, complete, and clear. When acceptance planning starts early, stakeholders can agree on how the finished system will be validated before design and coding begin. Data normalization is usually associated with database design. Functional testing is performed after software functions are implemented and executable. Reliability modeling may be performed in planning or design contexts, but the most directly appropriate requirements-phase activity among the options is acceptance test planning. It supports requirements validation and helps ensure that the delivered product meets customer expectations.

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