Abstract: A method for testing programming interfaces including application program interfaces and command line utilities. Each interface may be called from a loop instruction in a test instruction a number of times corresponding to a number of parameter sets which are needed to test each interface. The parameter sets are maintained in a separate data file and are retrieved for each call being made to an interface. One or more return value are included in the parameter set. The operating system generates one or more return values which are compared with the stored return value. A judgment is made based on the comparison of the stored return values and the programming interface-generated return value. When this comparison is not as expected, the return values are written to a file along with the parameter set which produced the unexpected comparison.