A method, computer program product, and computer system for testing converted source code features appearing in computer software of a computer system. N iterations are performed. Each iteration identifies M converted source code features appearing in P computer programs of the computer software. The M converted source code features have been converted by compiler conversion software in order that the P computer programs may be compiled into executable program codes by a new version of a compiler. Additionally, each selects P1 computer programs of the P computer programs for subsequent testing of the P1 computer programs. P1 is less than P. The P1 computer programs are selected such that the testing may be used to determine to a degree of confidence to which the compiler conversion software has correctly converted the M source code features in the P computer programs.