Use assertThrowsAsync for permission tests

Editor assessment

Use assertThrowsAsync for permission tests is a small, complete migration statement: the assertion helper, the test set, and the switch are all named, so the reader knows the tests now assert rejections idiomatically. The cli scope and test type are accurate, and no body is needed for so mechanical a change. No footer applies and hygiene is clean. A serviceable, publishable example. The helper and the test set are named, which is complete for a mechanical assertion migration of this size.