Path and Data Dependencies

The Display Portable System Monitor module is executed unconditionally every time the View a Portable System Monitor menu option is selected. The logic flow paths associated with Display Portable System Monitor are controlled by internal conditions in the system, rather than data (see Figure 12.11). These internal conditions are configuration- and environment-related items, such as whether the picture must be decompressed before it can be displayed, how much memory is available, and so on. For any particular system, these conditions will be fairly static once they have been established. This means that on a given system the same paths will be traversed through this element each time the Portable System Monitor is displayed. The functional complexity of the Display Portable System Monitor is said to be path dependent.

Figure 12.11: The expanded PSM logic flow map.

Another way to look at this type of function, from the perspective of the World Wide Web or a client/server environment, is that this is a downstream-only function. The server sends the requested data out, and no further action is required by the user or client.

The paths through Order a Portable System Monitor are controlled by user input, including the type and quantity of items ordered, what method of payment will be selected, and so on. This data will be very dynamic, and so the number of paths through Order a Portable System Monitor will be dynamic. The function paths of the Order a Portable System Monitor section are said to be data dependent.

The total number of paths that will be exercised by the test set through the system function is a function of the number of linearly independent paths plus the number of data set tests.