Application of Program Graphs and Complexity Analysis to Software Development and Testing

Several research studies have shown a strong relationship between program complexity, as measured by the structural properties of a program, and its error properties, as measured by number and types of errors and error detection and correction times. This research applies to: a) the setting of threshold values of complexity in software production in order to avoid undue difficulty with program debugging; b) the use of complexity as an index for allocating resources during the test phase of software development; c) the use of complexity for developing test strategies and the selection of test data. Application #c uses the directed graph representation of a program and its complexity measures to decompose the program into its basic constructs. The identification of the constructs serves to identify a) the components of the program which must be tested, and b) the selection of test data which are needed to exercise these components. Directed-graph properties which apply to program development and testing are defined; examples of the application of graph properties for program development and testing are given; the results of program complexity and error measurements are presented; and a procedure for complexity measurement and its use in programming and testing is summarized.