If a temporary directory should remain, we can check that after `run_me` the directory named "$TempDir" exists.

However, if temporary directory should be cleaned up, we cannot check it, because temporary directory is deleted when corresponding File::Temp::Dir object is destroying, which lefetime depends on lifetime of corresponding tzil attribute of the test, which lifetime is not well defined. The test object may still exist and will be destroyed some time later, and so, directory named "$TempDir" may still exist too. Thus, all we can check is `unlink_on_destroy` attribute value of temporary directory object.