Troubleshooting

mutastic says what went wrong, then exits with a status that says what kind of thing it was. The build plugins fail the build on any status but 0.

1: the score is below the threshold

For run, the score didn’t reach the threshold. Each missed mutant in the output says what to test and how to prove it; start with the ones on lines you changed. If the threshold is wrong for this module, set it, for example --threshold=70.

For verify, the mutant is still missed: no test fails with it in. The card for that mutant shows the inputs your tests used and a test that would catch it.

2: a usage error, or a build mutastic couldn’t read

The message says which. For an option, check mutastic --help: a value follows = or a space, except --since, which needs = (--since=main). For a build, mutastic must be run in, or pointed at, a Gradle or Maven build’s directory, and a module named as the build names it: :app for Gradle, a directory as -pl takes it for Maven. A mutant’s id belongs to the project its run was on, so run the command the run printed.

3: the tests fail without any mutant

mutastic runs your tests once before it changes anything. They have to pass first, as a mutant is only caught when a test that passed fails. Run the build’s own tests and fix what fails. A test that passes when run again is reported as flaky, and doesn’t stop a run.

4: mutastic itself went wrong

That’s a bug in mutastic. Please open an issue with the command, the message, and the worker log from the module’s work directory (build/mutastic/worker.log or target/mutastic/worker.log).