I do like how Rust’s test system ships with Cargo and how tests are local to a private submodule.

I wish the test report output was more comprehensible, and that there was a property test framework that felt more like in Haskell, e.g printing the PRNG seed when a test fails and letting you run with that seed again; it seems like proptest is the best there is, and it’s doing its own thing, kind of like how property tests work in OCaml.