A development environment for computer programs in which programs under test may be instrumented with probe functions. The probe functions are called through a wrapper function structured to comply with restrictive calling conventions of the platform for which the computer program is developed. By complying with the calling convention, proper operation of the computer program is achieved during testing even if an exception handler, or other program element that relies on compliance with the calling convention, is invoked. Once instrumented, the computer program may be tested to determine whether it executes desired logic function to determine the performance of the program or for other test functions.