1. A method for run time testing of a computer software application, the method comprising: attaching a Run-time Application Stubs (RAS) agent to the software application to be tested; running the software application with the attached RAS agent; configuring the RAS agent to monitor a component of the software application to collect results, while the software application is being executed; exercising the software application to perform a task; and recording a first set of calls to every function in the software application including arguments passed to the functions and return values by the functions, while the task is being performed by the software application; re-exercising the software application to perform the same task; recording a second set of calls to every function in the software application while the same task is being performed by the re-exercised software application; comparing the second set of calls to the first set of calls; and reporting an error when the second set of calls return different values from the first set of calls, to the same functions with the same arguments.