 As the system becomes more clearly specified and you have builds of the system to work with, you can elaborate on the details of the design.The activity of designing tests answers the question, “How am I going to perform the testing?” A complete test design informs readers about what actions need to be taken with the system and what behaviors and characteristics they should expect to observe if the system is functioning properly.A test design is different from the design work that should be done in determining how to build your test implementation.