Three methods of verifying requirements are commonly used. They are inspection, analysis, and test. Inspection is best suited to physical characteristics such as dimensions, weight, and finish. Ideally, it is through analyses that we validate the functional characteristics of a design because analyses are relatively inexpensive compared with testing. However, it is often only through testing that the product's design, and the tools used to create that design, can be truly validated. Testing uncovers unexpected problems or shortcomings. It helps us refine our analytical tools with which we design the product. Testing is the essential development tool that provides the feedback needed by engineers to refine their design and revise their analyses.
Maintainability and testability demonstration tests
are conducted to show whether or not a product possesses the requisite
maintainability characteristics. The specific approach used for demonstration
testing ranges from limited testing done independently by the contractor to
extensive tests controlled by the customer. See Appendix
B for specific test plans.
Recently, computer simulation in the form of virtual
reality (see 22.214.171.124 ) has allowed some maintainability characteristics of a design to be "evaluated" before any model or prototype is even constructed. Although not a total substitute for testing, virtual reality simulation can reduce the amount of time required by allowing some maintainability aspects of the design to be verified without or with reduced maintainability demonstration and testing.