To run all tests that support running against existing server:
$ meson test --setup running
To run just the main pg_regress tests against existing server:
$ meson test --setup running regress-running/regress
To ensure the 'running' setup continues to work, test it as part of the
freebsd CI task.
Discussion: https://postgr.es/m/CAH2-Wz=XDQcmLoo7RR_i6FKQdDmcyb9q5gStnfuuQXrOGhB2sQ@mail.gmail.com