Arvados

arv-copy is currently completely untested. This is especially unfortunate because it's a real workhorse Arvados tool: it's the only thing that does this job, and people really want that job done. It should have tests.

This will probably require some reorganizing of arv-copy, because right now a lot of its architecture makes it difficult to test: it keeps state in global variables, lots of functions call out directly to third-party tools like Git, etc.