If you're using Linux, I would recommend using TemporaryFile instead of NamedTemporaryFile. It takes advantage of the O_TMPFILE flag, which guarantees that the

If you're using Linux, I would recommend using TemporaryFile instead of NamedTemporaryFile. It takes advantage of the O_TMPFILE flag, which guarantees that the kernel will clean up the file for you when the process exits: import shutil import tempfile @pytest.fixture def libfact(): tmp = tempfile.TemporaryFile() tmp_name = f"/dev/fd/{tmp.name}" shutil.copy2("./fact.so", tmp_name) lib = CDLL(tmp_name) yield lib It's better than relying on your application to clean up the file for you. With application-level cleanup hooks, you're still vulnerable to a resource leak if the process gets a SIGKILL or crashes or otherwise ends before your hooks run.