The design document aids in programming, communication, and error analysis and test data generation. The requirements statement and the design document should together give the problem and the organization of the solution i.e. what the program will do and how it will be done.
The design document should contain:
Principal data structures.
Functions, algorithms, heuristics or special techniques used for processing.
The program organization, how it will be modularized and categorized into external and internal interfaces.
Any additional information.
Here the testing activities should consist of:
- Analysis of design to check its completeness and consistency - the total process should be analyzed to determine that no steps or special cases have been overlooked. Internal interfaces, I/O handling and data structures should specially be checked for inconsistencies.
- Analysis of design to check whether it satisfies the requirements - check whether both requirements and design document contain the same form, format, units used for input and output and also that all functions listed in the requirement document have been included in the design document. Selected test data which is generated during the requirements analysis phase should be manually simulated to determine whether the design will yield the expected values.
- Generation of test data based on the design - The tests generated should cover the structure as well as the internal functions of the design like the data structures, algorithm, functions, heuristics and general program structure etc. Standard extreme and special values should be included and expected output should be recorded in the test data.
- Re-examination and refinement of the test data set generated at the requirements analysis phase.
The first two steps should also be performed by some colleague and not only the designer/developer.
