Example for using Rely with dune's built in runtest
To run:
npm install -g esy
esy install
esy build
esy test
This doesn't show incremental progress for slower running tests (play with the values in my_test.re to see how this plays out). I think overall running a separate executable is a better user experience, but this shows that it is possible to use the built in dune test stanza with Rely.