Mutaatiotestit

Mutaatiotestit, also known as mutation testing, is a software testing technique used to evaluate the quality of existing tests. It involves introducing small, deliberate changes, called mutations, into the source code of a program. These mutations are typically simple modifications, such as changing an operator, a constant, or a variable. After each mutation is introduced, the existing test suite is run against the modified code.

The goal of mutation testing is to determine if the current tests are effective at detecting these introduced faults. If a test suite fails to detect a mutation (i.e., it still passes even though the code has been altered), it indicates that the tests might not be thorough enough. The mutated code that is not detected by any test is called a "survivor."

The process generally involves several steps. First, a "mutant" or mutated version of the original program is created by applying a mutation operator. Then, the original test suite is executed against this mutant. If all tests pass, the mutant has "survived." If at least one test fails, the mutant is considered "killed." The effectiveness of the test suite is then measured by the "mutation score," which is the percentage of mutants killed. A higher mutation score indicates a more robust test suite.

Mutation testing can be a computationally intensive process, as it requires generating and testing a large number of mutants. However, it provides valuable insights into the strengths and weaknesses of a test suite, helping developers identify areas where tests need to be improved or added. It is considered a powerful technique for enhancing test suite quality and increasing confidence in the correctness of software.