Does dune runtest launch a separate process for each test file?

I am using dune runtest with ounit2. Some of the tests I’m writing modify global refs in weird ways. If other tests were run with these modified global ref values it might cause weird behavior. Does dune runtest launch separate processes for each test file, thus re-initializing these global refs to their default values? Tests within the same file or at least same >::: test suite seem to all run within the same process.