Which method is used to design new software tests and ensure their quality?

Mutation testing is an effective method for designing new software tests and ensuring the quality of those tests. This technique involves making small modifications (mutations) to the program's code and then running the existing test suite to determine if the tests can detect the changes. If a test fails in response to a mutation, it indicates that the test is capable of identifying faults in the software. On the other hand, if a test passes despite the mutation, it may indicate that the test is insufficiently robust and needs to be revised or improved.

By focusing on whether the tests can catch these intentional errors, mutation testing helps developers evaluate the completeness and effectiveness of their test suites. This approach not only helps enhance the quality of the existing tests but also aids in designing new tests that are more effective in identifying potential defects. As a result, mutation testing serves as a strong technique for improving software reliability and robustness through more stringent evaluation of test quality.