28. Use cases

• A use case is a description of a particular use of a system. For example, of a use

  • take phone off the hook,

  • dial a number,

  • the phone at the other end rings,

  • the phone at the other end is taken off hook.

• Defining a set of use cases helps us understand what we are trying to build:

  • During design description use cases verify the system from the user's point of view.

  • Later use cases become a source of test cases.