Add some standalone tests for runguard.

[meisterT]

This is not only useful in general for quicker testing of runguard, but will help to gain some confidence in runguard changes as we plan to do with https://docs.google.com/document/d/1WZRwdvJUamsczYC7CpP3ZIBU8xG6wNqYqrNJf7osxYs/edit