It’s a bit tangent (more related to dune Cram tests than the Dune “core” itself), but I’d really like Cram tests to have a specific syntax for external oracles. All other solutions (using non-Cram tests, putting the entire oracles in the run.t file, etc) are much less convenient.
Otherwise, concerning Dune tests: showing counts of failing tests, showing counts of tests already cached, and some overall way to make things more “intuitive” for beginners (to help them understand what is being done or not being done, such as “this test has been disabled due to such enabled_if condition not being met”), all could help.
Another minor usability issue for me is that, because Dune targets start with @, I cannot type dune build @<dir>/ and then tab to get some completion based on existing file paths. But this must be easily solvable, I just didn’t take the time to look into it.