Embodiments of the invention are directed to metamorphic relationship based code testing using mutant generators. The system is configured for identifying and remediating defects in an original program based on constructing at least one mutated program by distorting the original program, and analyzing expression of mutants in test results. In particular, the system receives a request to perform defect analysis of an original program. In response, the system constructs a first mutated program by embedding one or more mutants in the original program code. Moreover, the system typically maps the one or more mutants to one or more metamorphic relationships of process functions of the original program. The system may then implement tests of the original program and the first mutated program by providing one or more predetermined test cases as input to both, to determine whether the original program comprises at least one defect.