The biggest case where this matters is for unit tests. If your unit tests are calling external-crate functions that have expensive tests on them, you might want any of the following:
don't run any tests from that crate (you don't care about them)
run all tests from that crate unthrottled (you are responsible for that crate and you are intentionally testing them)
run them, but throttle them (you care about those tests but they are too expensive to do all of them)
Currently there isn't much division between preconditions and postconditions, but hypothetically, you could care only about preconditions from a particular third-party crate; however, the API for exposing an option to "run tests for this crate, but only test the cheaper preconditions" should be considered properly, not just enabled through and add-hoc configuration option on initialization
Not sure if this is the right way to go.
The biggest case where this matters is for unit tests. If your unit tests are calling external-crate functions that have expensive tests on them, you might want any of the following:
Currently there isn't much division between preconditions and postconditions, but hypothetically, you could care only about preconditions from a particular third-party crate; however, the API for exposing an option to "run tests for this crate, but only test the cheaper preconditions" should be considered properly, not just enabled through and add-hoc configuration option on initialization