A system and method for testing modified code paths without testing unmodified code paths is described. During testing of the baseline build of a program, code coverage data is generated. The code coverage data identifies which test implicates which code path of the baseline build. When a modification of the baseline build is made, the modified build may be differentiated to determine what code of the modified build was changed. When the modified build is differentiated, the code coverage data for the modified code path is mapped to appropriate tests. The tests may then be used to test the changed code path without requiring testing of all the code paths of the modified build.