An approach to improve the testability of a program is to augment that program with mechanisms specific to testing tools, i.e. to enhance the program with self-testability. In particular, this can decrease the amount of information which a human tester needs to thoroughly test and can simplify the testing process. Most approaches to self-testability, however, assume a given test suite and implement means for test execution. Few approaches address test case generation and test evaluation. This paper presents an approach to self-testability which encompasses test case generation and test evaluation. The approach presented is an integration of the self-testing COTS components (STECC) method and the metamorphic testing approach.