This feels like a handy tool! The first thing I read when opening new code is the test suite - it's worth getting that right at the start. Would you consider deeper unit testing? S3 (and aws) have the indispensible `moto` boto mocks, I think something similar would be dead handy here.
Yes, on my TODO list is much deeper unit testing. I made this in four days and was just testing that it worked. It already has about 92% code coverage but I want to cover that fields are returned properly and such. Some help would be appreciated if people would like to, including mocking it up.