How can OCaml dune test program find test input files?

── test├── dune├── test_program.ml└── foo_files├── foo_a└── foo_b

How can test_program find the files under folder foo_files when run using dune test?

I can see that when the program is run, the current working directory is _build/default/test and the foo_files folder is not copied there.

dune 3.15.3