Incorrect statement example 1

Consider the following statement, as defined in the software requirements specification:

  • The z dimension value of the vortex is the sum of its x and y dimension values.

Due to an unknown reason, the programmer wrote a statement that does not correctly implements the requirement:

  • z = x - y.

The incorrect statement written by the programmer is a mistake. This mistake provides a new (and probably incorrect) implementation of the requirement, thus characterizing a fault. If such a fault is activated (executed), with x = 0, regardless of y value, no incorrect output is produced because, although the fault is activated, it does not lead to an error and no failure occurs. For any other value different from x = 0, the fault activation causes an error on the variable z. Such an error, when propagated until the product output, results in a failure.