I agree that tests are sort of documentation and interesting to see but when I look at the documentation of a package I don’t really expect to see some “assert”. For instance in the very good pandas package, there are a lot of examples but no test in the doc. I like this pattern.

One class per file? One method per file? Yes I do prefer splitting and organizing my code, maybe it is just a preference and not a best practice.

For coverage, don’t you just use a--cov option ?