Unit tests

[mattdesl]

This is a rather tough one to test since it ends up creating a lot of garbage in my github org/user. The lack of tests have created some bugs/regressions so it would be good to figure this out before making any more significant changes.

I think one way of testing this would be to use a dummy GitHub account like ghrepo-test-account. We can delete repos after they are created with gh-api.