just in case you're interested, Julia does (now) have tools similar to what you're describing, although of course there are still be lots of possible improvemen

just in case you're interested, Julia does (now) have tools similar to what you're describing, although of course there are still be lots of possible improvements to be made w.r.t. their UX to make these tools more reliable and easier to use in particular @assert_type_stable and @assert_doesn't_error is largely provided by JET.jl and the effects system, and @assert_doesn't_allocate is (at least partially) provided in AllocCheck.jl