"""Shared free-port helper for svc tests (not a test module)."""
import socket


def free_test_port():
    """Return a port the kernel reports free on 127.0.0.1 right now.

    Each call opens a fresh reservation and closes it before returning, so the
    caller (e.g. `svc deploy`) can bind the port itself. Ports are not pooled.
    """
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as reservation:
        reservation.bind(("127.0.0.1", 0))
        return reservation.getsockname()[1]