Structural testing is considered more technical than functional testing. It attempts to design test cases from the source code and not from the specifications. The source code becomes the base document which is examined thoroughly in order to understand the internal structure and other implementation details. It also gives insight in to the source code which may be used as an essential knowledge for the design of test cases. Structural testing techniques are also known as white box testing techniques due to consideration of internal structure and other implementation details of the program. Many structural testing techniques are available and some of them are given in this chapter like control flow testing, data flow testing, slice based testing and mutation testing.

CONTROL FLOW TESTING

This technique is very popular due to its simplicity and effectiveness. We identify paths of the program and write test cases to execute those paths. As we all know, path is a sequence of statements that begins at an entry and ends at an exit. As shown in chapter 1, there may be too many paths in a program and it may not be feasible to execute all of them. As the number of decisions increase in the program, the number of paths also increase accordingly.

Every path covers a portion of the program. We define ‘coverage’ as a ‘percentage of source code that has been tested with respect to the total source code available for testing’.