Some functions may be inherently hard to cover with tests, for example if:
- Generated mutants cause tests to hang.
- You've chosen to test the functionality by human inspection or some higher-level integration tests.
- The function has side effects or performance characteristics that are hard to test.
- You've decided the function is not important to test.
There are three ways to skip mutating some code:
- Marking the function with an attribute within the source file.
- Filtering by path in the config file or command line.
- Filtering by function and mutant name in the config file or command line.
The results of all these filters can be previewed using the
- If some particular functions are hard to test with cargo-mutants, use an attribute, so that the skip is visible in the code.
- If a whole module is untestable, use a filter by path in the config file, so that the filter's stored in the source tree and covers any new code in that module.
- If you want to permanently ignore a class of functions, such as
Debugimplementations, use a regex filter in the config file.
- If you want to run cargo-mutants just once, focusing on a subset of files, functions, or mutants, use command line options to filter by name or path.