In #201, I deleted code to migrate to Run, and no tests failed, suggesting none of the commands are tested.

In looking for test files, this was the only one that exists outside of all_test.go:

• ./internal/command/createreleasepr_test.go

At the moment, it seems like tests do not exists to catch any problems in the librarian code outside of that. If that's the case, we need to add tests to librarian that run as part of CI for this codebase.

/cc @jskeet @ldetmer