Keep improving tests

[sckott]

• http request caching: looks like paws is using httr under the hood https://cran.r-project.org/web/packages/paws.common/index.html - should be able to use vcr to cache requests, speed up tests, hide secrets, etc.
• be very sure no secrets are in fixtures
• aws env vars need to be present within this github repo, but they don't need to be real
• what else?

[sckott]

Infrastructure added. Add more tests, then close - will be an ongoing item to do of course